# Where will it rain this weekend (Sep 19 - Sep 20)?

Sep 19 – Sep 20, 2026

Updated: September 16, 2026

Category: Climate and Weather

Tags: Snow and rain

HTML: /markets/climate-and-weather/snow-and-rain/where-will-it-rain-this-weekend-sep-19-sep-20/

## Short Answer

**Key takeaway.** Rain is likely in Miami this weekend, September 19-20, with the **market** pricing an **81%** **probability**.

## Key Claims (September 2026)

**- Miami and West Palm Beach lead; active tropical cyclones are not expected for the weekend.** Newark and New York City expect unsettled conditions, with historically higher September precipitation.

## Market Behavior & Drivers

The absence of tropical cyclones or fast-moving storms, alongside El Niño's limited daily influence, shapes weekend rain expectations.

The market's price increase on September 16 was driven by regional weather forecasts. An updated prediction for Trenton, New Jersey, for the weekend of September 19-20 showed a 70 percent chance of showers on Sunday as part of a broader storm system. This news coincided with an 11 percentage point rise in the contract's price, from 54.0% to 65.0%.

The market's initial and largest jump, from 0.0% to over 50% between September 14 and September 15, is not explained by a specific event in the provided context for the New York City area. The broader meteorological environment includes a strengthening El Niño, which is influencing global weather patterns for September 2026. Price action accelerated as the event moved into the effective range of high-resolution daily forecasts, which are considered reliable up to 15 days out.

### Who Wins and Why

| Outcome | Market | Model | Why |
| --- | --- | --- | --- |
| Miami | 81.0% | 81.0% | High humidity often leads to afternoon and evening showers and thunderstorms. |
| Trenton | 47.0% | 47.0% | The proximity to coastal moisture increases the likelihood of rain. |
| West Palm Beach | 78.0% | 78.0% | A moist tropical air mass is expected to bring widespread precipitation. |

## Model vs Market

| Outcome | Market Probability | Octagon Model Probability |
| --- | --- | --- |
| Miami | 81.0% | 81.0% |
| Trenton | 47.0% | 47.0% |
| West Palm Beach | 78.0% | 78.0% |
| Washington DC | 55.0% | 55.0% |
| Atlanta | 32.0% | 32.0% |
| New York City | 60.0% | 56.8% |
| Boston | 57.0% | 57.0% |
| Philadelphia | 55.0% | 55.0% |
| Newark | 64.0% | 64.0% |
| Chicago | 65.0% | 65.0% |
| New Orleans | 30.0% | 27.0% |
| Houston | 20.0% | 17.0% |
| Austin | 19.0% | 19.0% |
| Minneapolis | 57.0% | 57.0% |
| Oklahoma City | 39.0% | 39.0% |
| Dallas | 0.0% | 0.0% |
| San Antonio | 0.0% | 0.0% |
| Phoenix | 16.0% | 16.0% |
| Denver | 58.0% | 58.0% |
| Las Vegas | 5.0% | 5.0% |
| Seattle | 10.0% | 10.0% |
| Los Angeles | 18.0% | 18.0% |
| San Francisco | 0.0% | 0.0% |

- Expiration: September 21, 2026

## Significant Price Movements

### Outcome: Trenton

#### 📈 September 16, 2026: 34.0pp spike

Price increased from 13.0% to 47.0%

**What happened:** The primary driver of the 34.0 percentage point spike was updated weather forecasts for Trenton, New Jersey, for the weekend of September 19-20, 2026. Forecasts on September 16, 2026, indicated a 70 percent chance of showers for Trenton on Sunday, September 20, along with a broader storm system expected to bring steady to heavy rain to the region between late Saturday and mid-morning Sunday [[1]](https://wpst.com/ixp/385/p/nj-weather-bright-friday-weekend-rain/). This traditional news and data release directly informed market participants of a higher likelihood of rain, leading to the significant price adjustment. No information regarding social media activity was available for assessment.

### Outcome: Atlanta

#### 📉 September 15, 2026: 70.0pp drop

Price decreased from 99.0% to 29.0%

**What happened:** The primary driver of the 70.0 percentage point drop for the "Atlanta" outcome was the traditional news coverage released on September 15, 2026 [[2]](https://www.atlantanewsfirst.com/2026/09/15/heat-dry-weather-continues-this-week-rain-cooler-weather-next-week/). Atlanta News First published a forecast on that day, indicating that while scattered showers were possible, widespread rain was not expected for the weekend of September 19-20, 2026, with more significant rain arriving only on Monday, September 21 [[2]](https://www.atlantanewsfirst.com/2026/09/15/heat-dry-weather-continues-this-week-rain-cooler-weather-next-week/). This information directly communicated a low likelihood of substantial rainfall within the market's specified timeframe, causing the outcome's perceived probability to decline sharply. Social media was not identified as a factor based on the provided research.

### Outcome: Phoenix

#### 📈 September 14, 2026: 54.0pp spike

Price increased from 20.0% to 74.0%

**What happened:** Based on the provided research, the primary driver for the 54.0 percentage point spike in the prediction market for rain in Phoenix on September 19-20, 2026, cannot be identified. Current weather forecasts as of September 16, 2026, explicitly indicate that the active monsoon pattern will dry out by September 18, with the weekend expected to be dry and warm [[3]](https://www.abc15.com/weather/most-accurate-forecast-flood-watch-in-the-valley-until-11-p-m)[[4]](https://www.fox10phoenix.com/weather/arizona-weather-forecast-91526)[[5]](https://hoodline.com/2026/09/phoenix-braces-as-midweek-monsoon-aims-to-drench-valley-trigger-flash-floods/). There is no evidence of influential social media posts or traditional news reports that would explain this market movement; in fact, available weather data contradicts an expectation of rain for that specific weekend [[3]](https://www.abc15.com/weather/most-accurate-forecast-flood-watch-in-the-valley-until-11-p-m)[[4]](https://www.fox10phoenix.com/weather/arizona-weather-forecast-91526)[[5]](https://hoodline.com/2026/09/phoenix-braces-as-midweek-monsoon-aims-to-drench-valley-trigger-flash-floods/)[[6]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php). Furthermore, the term "54.0pp" does not correspond to a recognized meteorological measurement for precipitation [[7]](https://www.iskynews.com/2026/09/severe-thunderstorm-hitting-east-valley.html)[[8]](https://www.weather.gov/psr/PRI). Therefore, social media was irrelevant to this movement based on the provided information, and the market spike appears ungrounded in current forecasts.

Sources:

1. [Damp start but bright finish Friday, timing is everything for NJ's weekend rain](https://wpst.com/ixp/385/p/nj-weather-bright-friday-weekend-rain/)
2. [Heat, dry weather continues this week; Rain, cooler weather next week](https://www.atlantanewsfirst.com/2026/09/15/heat-dry-weather-continues-this-week-rain-cooler-weather-next-week/)
3. [FORECAST: Flood Watch in the Valley](https://www.abc15.com/weather/most-accurate-forecast-flood-watch-in-the-valley-until-11-p-m)
4. [Arizona weather forecast: Storms and highs in the 90s coming to Phoenix | FOX 10 Phoenix](https://www.fox10phoenix.com/weather/arizona-weather-forecast-91526)
5. [Phoenix Weather Forecast: Storms And Heavy Rain Threaten Wednesday](https://hoodline.com/2026/09/phoenix-braces-as-midweek-monsoon-aims-to-drench-valley-trigger-flash-floods/)
6. [Probabilistic Hazards Outlook](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)
7. [Severe Thunderstorm Hitting the East Valley; 60 MPH Wind Gusts Possible](https://www.iskynews.com/2026/09/severe-thunderstorm-hitting-east-valley.html)
8. [Phoenix Rainfall Index](https://www.weather.gov/psr/PRI)

## Contract Snapshot

This market determines if rain will occur in New York City, Denver, or Minneapolis during the weekend of Sep 19 - Sep 20. It begins on Saturday, Sep 19, 12:00am EDT, with a maximum payout date of Sep 21, 2026. The provided information does not detail the exact criteria for what constitutes a 'YES' (rain) or 'NO' (no rain) resolution, nor does it list any special settlement conditions.

## Market Discussion

Localized forecasts for September 19, 2026, indicate a rainy day in Texarkana, Texas [[1]](https://meteum.ai/weather/en/texarkana/date/september/19), while an upper-level trough is expected to bring unsettled weather to the Great Lakes and Northeast during the weekend of September 19-20, 2026 [[2]](https://preview-forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=ALY&product=AFD&site=IND&version=20)[[3]](https://forecast.weather.gov/product.php?format=TXT&glossary=1&highlight=off&issuedby=BUF&product=AFD&site=NWS&version=19). Specifically, eastern New York and western New England are expected to experience more active weather, with widespread showers and thunderstorms particularly likely on Sunday, September 20, 2026 [[2]](https://preview-forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=ALY&product=AFD&site=IND&version=20)[[3]](https://forecast.weather.gov/product.php?format=TXT&glossary=1&highlight=off&issuedby=BUF&product=AFD&site=NWS&version=19), amidst broader concerns about a record-breaking El Niño event potentially driving extreme rainfall in the coming months [[4]](https://deer.social/profile/did:plc:iczg6a2i3etk5bscga6uv6od/post/3mvflswxs3k2h)[[5]](https://mastodon.social/@weatherwest/117198062361657622)[[6]](https://deer.social/profile/did:plc:lb7jeizjwxjcn3bvkohqxkba/post/3muws3ugafs2t)[[7]](https://deer.social/profile/did:plc:nrk23x3bo3kief5ywy2cqfdi/post/3mutp4r2m7k2j).

Sources:

1. [Weather in Texarkana, State of Texas, United States, for September 19 — Temperature, precipitation, wind](https://meteum.ai/weather/en/texarkana/date/september/19)
2. [National Weather Service](https://preview-forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=ALY&product=AFD&site=IND&version=20)
3. [National Weather Service](https://forecast.weather.gov/product.php?format=TXT&glossary=1&highlight=off&issuedby=BUF&product=AFD&site=NWS&version=19)
4. [Jeff Berardelli: "It’s astonishing to see this, even though we saw it coming months ago. White = 10°F + above normal in the El Niño regions. Its immense! In the air, a regional warming of 10° is no big deal. But in the ocean it’s immense! Think about how hard it is/ how long it takes to cool/ heat your pool. 1/" — deer.social](https://deer.social/profile/did:plc:iczg6a2i3etk5bscga6uv6od/post/3mvflswxs3k2h)
5. [Daniel Swain: "In fact, the odds of "more tha…" - Mastodon](https://mastodon.social/@weatherwest/117198062361657622)
6. [Prof. Eliot Jacobson: "Breaking News! Code: Hot! The Nino 3.4 SST-anomaly is rising fast, now at 2.89°C above the 1991-2020 baseline. The all-time daily peak (3.03°C, Nov. 19, 2015) is within reach in a few days. The Climate 8-Ball is sober, hasn't had a drink, waiting for the Jack of Hearts." — deer.social](https://deer.social/profile/did:plc:lb7jeizjwxjcn3bvkohqxkba/post/3muws3ugafs2t)
7. [Professor Euan Ritchie FAMS: "“In the lifetime of the active scientists working on atmosphere and ocean, we’d never seen anything like this,” - John McBride www.abc.net.au/news/2026-09..." — deer.social](https://deer.social/profile/did:plc:nrk23x3bo3kief5ywy2cqfdi/post/3mutp4r2m7k2j)

## Market Data

| Contract | Yes Bid | Yes Ask | Last Price | Volume | Open Interest |
| --- | --- | --- | --- | --- | --- |
| Atlanta | 23% | 34% | 32% | 175 contracts | 130 contracts |
| Austin | 14% | 18% | 19% | 55 contracts | 55 contracts |
| Boston | 61% | 66% | 57% | 122 contracts | 121 contracts |
| Chicago | 62% | 65% | 65% | 856 contracts | 809 contracts |
| Dallas | 10% | 19% | 0% | 0 contracts | 0 contracts |
| Washington DC | 59% | 70% | 55% | 242 contracts | 209 contracts |
| Denver | 56% | 58% | 58% | 359 contracts | 359 contracts |
| Newark | 55% | 65% | 64% | 98 contracts | 67 contracts |
| Houston | 14% | 16% | 20% | 62 contracts | 62 contracts |
| Los Angeles | 13% | 15% | 18% | 10 contracts | 10 contracts |
| Las Vegas | 5% | 6% | 5% | 124 contracts | 99 contracts |
| Miami | 72% | 80% | 81% | 572 contracts | 557 contracts |
| Minneapolis | 48% | 55% | 57% | 23 contracts | 23 contracts |
| New Orleans | 30% | 39% | 30% | 64 contracts | 62 contracts |
| New York City | 54% | 60% | 60% | 158 contracts | 158 contracts |
| Oklahoma City | 23% | 32% | 39% | 19 contracts | 19 contracts |
| Philadelphia | 60% | 69% | 55% | 105 contracts | 90 contracts |
| Phoenix | 15% | 18% | 16% | 707 contracts | 707 contracts |
| San Antonio | 16% | 23% | 0% | 0 contracts | 0 contracts |
| Seattle | 8% | 10% | 10% | 89 contracts | 80 contracts |
| San Francisco | 5% | 6% | 0% | 0 contracts | 0 contracts |
| Trenton | 45% | 75% | 47% | 325 contracts | 325 contracts |
| West Palm Beach | 72% | 81% | 78% | 307 contracts | 301 contracts |

## Which developing storm systems are the National Hurricane Center (NHC) and Weather Prediction Center (WPC) tracking that could bring rain to coastal cities like Miami or New Orleans between Sep 19-20, 2026?

Active tropical cyclones | None in Atlantic as of September 16, 2026 [[1]](https://prod-east-nhc.woc.noaa.gov/cyclones/)[[2]](https://prod-east-nhc.woc.noaa.gov/text/refresh/MIATWDAT+shtml/160421_MIATWDAT.shtml)[[3]](https://www.nhc.noaa.gov/text/MIATWOAT.shtml) |
Tropical cyclone formation expectation | Not expected in next 7 days [[1]](https://prod-east-nhc.woc.noaa.gov/cyclones/)[[2]](https://prod-east-nhc.woc.noaa.gov/text/refresh/MIATWDAT+shtml/160421_MIATWDAT.shtml)[[3]](https://www.nhc.noaa.gov/text/MIATWOAT.shtml) |
Storm systems tracking towards Miami/New Orleans (Sep 19-20, 2026) | None highlighted [[2]](https://prod-east-nhc.woc.noaa.gov/text/refresh/MIATWDAT+shtml/160421_MIATWDAT.shtml)[[4]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html)[[5]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php) |

**No tropical cyclones are active or expected in the Atlantic**

No tropical cyclones are active or expected in the Atlantic. As of September 16, 2026, the National Hurricane Center (NHC) indicates no active tropical cyclones in the Atlantic basin. Furthermore, tropical cyclone formation is not anticipated in the coming days or over the next seven days [[1]](https://prod-east-nhc.woc.noaa.gov/cyclones/)[[2]](https://prod-east-nhc.woc.noaa.gov/text/refresh/MIATWDAT+shtml/160421_MIATWDAT.shtml)[[3]](https://www.nhc.noaa.gov/text/MIATWOAT.shtml).

No specific storm systems are tracking toward coastal cities. Current forecasts from the NHC, NOAA, and the Climate Prediction Center (CPC) do not identify specific storm systems that are tracking toward coastal cities such as Miami or New Orleans, which could bring rain between September 19-20, 2026 [[2]](https://prod-east-nhc.woc.noaa.gov/text/refresh/MIATWDAT+shtml/160421_MIATWDAT.shtml)[[4]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html)[[5]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php). The CPC's 6-10 day outlook, valid for September 19-23, 2026, also does not indicate a specific tropical storm system impacting these cities during that weekend [[4]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html).

Minor weather systems are present but lack significant impact. Although a broad upper-level trough over the southeastern Bahamas and Hispaniola is forecast to generate scattered showers and isolated thunderstorms, no organized storm systems are presently being tracked for significant impact on Miami or New Orleans for September 19-20, 2026. Furthermore, a stationary front located near Florida is projected to dissipate by Thursday, September 17, 2026 [[2]](https://prod-east-nhc.woc.noaa.gov/text/refresh/MIATWDAT+shtml/160421_MIATWDAT.shtml).

Sources:

1. [https://prod-east-nhc.woc.noaa.gov/cyclones/](https://prod-east-nhc.woc.noaa.gov/cyclones/)
2. [https://prod-east-nhc.woc.noaa.gov/text/refresh/MIATWDAT+shtml/160421_MIATWDAT.shtml](https://prod-east-nhc.woc.noaa.gov/text/refresh/MIATWDAT+shtml/160421_MIATWDAT.shtml)
3. [Atlantic Tropical Weather Outlook - National Hurricane Center - NOAA](https://www.nhc.noaa.gov/text/MIATWOAT.shtml)
4. [Climate Prediction Center - 6-10 and 8-14 Day Prognostic Discussions](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html)
5. [Probabilistic Hazards Outlook](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)

## What meteorological evidence in the Climate Prediction Center's 8-14 day outlook supports the forecast of fast-moving storms in the Ohio Valley affecting cities like Chicago or Philadelphia around Sep 19-20, 2026?

Ohio Valley Storm Forecast (Sept 19-20, 2026) | No meteorological evidence for fast-moving storms (Climate Prediction Center) [[1]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php) |
Ohio Valley Precipitation Outlook (Late Sept 2026) | Below-normal precipitation due to strong high pressure (Climate Prediction Center) [[2]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html) |
Source of Confusion | Significant severe weather event in Ohio Valley occurred August 19-20, 2026 [[3]](https://www.weather.gov/iln/20260820)[[4]](https://www.weather.gov/pah/Aug19-20_2026Severe)[[5]](https://www.weather.gov/media/iln/OHBriefing.pdf)[[6]](https://forecast.weather.gov/product.php?format=CI&glossary=1&issuedby=DY1&product=SWO&site=NWS&version=31)[[7]](https://www.nbc4i.com/weather/stormy-august-brings-record-rainfall-historic-windstorm-with-tornadoes/) |

**The Climate Prediction Center's outlook does not support fast-moving storms**

The Climate Prediction Center's outlook does not support fast-moving storms.
The Climate Prediction Center's 8-14 day outlook and prognostic discussions for the period of September 19-20, 2026, do not contain meteorological evidence supporting a forecast of fast-moving storms in the Ohio Valley that would affect cities like Chicago or Philadelphia [[1]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php). Instead, current meteorological guidance for this specific weekend describes cooler and drier conditions for many areas east of the Rockies, with no indication of fast-moving, precipitation-heavy storms across the Ohio Valley [[1]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php).

Strong high pressure over the Ohio Valley favors dry conditions.
Specifically, the CPC's 8-14 day prognostic discussion for September 21-27, 2026, indicates that strong surface high pressure favors below-normal precipitation across the Great Lakes and Ohio Valley [[2]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html). This pattern is characterized by a mid-level ridge amplifying over central and eastern Canada, bringing positive height anomalies to the central and eastern United States. Such conditions are generally associated with drier weather in the region rather than fast-moving storms [[1]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)[[2]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html).

The premise of fast-moving storms might stem from an earlier event.
The idea of "fast-moving storms in the Ohio Valley" for this period appears to be confused with a significant weather event that occurred approximately one month earlier, on August 19-20, 2026, which involved severe thunderstorms, flash flooding, and tornadoes in the Ohio Valley [[3]](https://www.weather.gov/iln/20260820)[[4]](https://www.weather.gov/pah/Aug19-20_2026Severe)[[5]](https://www.weather.gov/media/iln/OHBriefing.pdf)[[6]](https://forecast.weather.gov/product.php?format=CI&glossary=1&issuedby=DY1&product=SWO&site=NWS&version=31)[[7]](https://www.nbc4i.com/weather/stormy-august-brings-record-rainfall-historic-windstorm-with-tornadoes/). While forecast models for Chicago suggest patchy rain on September 19 and potential thundery outbreaks on September 20, 2026, these localized possibilities are considered independent of the high-pressure pattern mentioned in official CPC guidance for the Ohio Valley [[8]](https://www.easeweather.com/north-america/united-states/illinois/cook-county/chicago/september).

Sources:

1. [Probabilistic Hazards Outlook - Climate Prediction Center - NOAA](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)
2. [Climate Prediction Center - 6-10 and 8-14 Day Prognostic Discussions](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html)
3. [August 19-20, 2026 -- Flooding](https://www.weather.gov/iln/20260820)
4. [Summary of Severe Thunderstorms on August 19-20, 2026](https://www.weather.gov/pah/Aug19-20_2026Severe)
5. [08.19.2026 7.45 PM EDT - State of Ohio Briefing](https://www.weather.gov/media/iln/OHBriefing.pdf)
6. [National Weather Service](https://forecast.weather.gov/product.php?format=CI&glossary=1&issuedby=DY1&product=SWO&site=NWS&version=31)
7. [Stormy Ohio August brings record rainfall, historic windstorm and...](https://www.nbc4i.com/weather/stormy-august-brings-record-rainfall-historic-windstorm-with-tornadoes/)
8. [Weather in Chicago in September 2026 - Detailed Forecast](https://www.easeweather.com/north-america/united-states/illinois/cook-county/chicago/september)

## How do the expected El Niño effects on the West Coast versus the Gulf Coast translate to different rainfall probabilities for San Francisco and New Orleans in mid-September 2026?

El Niño Persistence Probability | Greater than 90% through Northern Hemisphere fall and winter 2026-27 (as of Sept 16, 2026) [[1]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)[[2]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/probabilities/)[[3]](https://www.cpc.ncep.noaa.gov/products/analysis%5Fmonitoring/lanina/enso%5Fevolution-status-fcsts-web.pdf)[[4]](https://www.gfdl.noaa.gov/prediction/september-2026-el-nino-predictions/)[[5]](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/) |
San Francisco Rainfall (Sept 19-20, 2026) | Negligible or no measurable rainfall [[6]](https://www.weathertab.com/en/c/09/united-states/california/san-francisco/)[[7]](https://en.climate-data.org/north-america/costa-rica/san-jose/san-francisco-555187/t/september-9/)[[8]](https://www.weathertab.com/en/long-range-weather/09/19/united-states/california/94130-san-francisco/)[[9]](https://www.easeweather.com/north-america/united-states/california/san-francisco/september) |
New Orleans Rain Chance (Sept 19, 2026) | 40%, with a decreasing trend to 15% or less [[10]](https://www.easeweather.com/north-america/united-states/louisiana/orleans-parish/new-orleans/september)[[11]](https://www.wunderground.com/hourly/us/la/new-orleans/70130/date/2026-9-19)[[12]](https://www.weather.gov/lix) |

**A strong El Niño is active, but its influence on specific daily weather is limited**

A strong El Niño is active, but its influence on specific daily weather is limited. As of September 16, 2026, a strong El Niño event is active and strengthening, with a greater than **90%** **probability** of persisting as a very strong event through the Northern Hemisphere fall and winter 2026-27 [[1]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)[[2]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/probabilities/)[[3]](https://www.cpc.ncep.noaa.gov/products/analysis%5Fmonitoring/lanina/enso%5Fevolution-status-fcsts-web.pdf)[[4]](https://www.gfdl.noaa.gov/prediction/september-2026-el-nino-predictions/)[[5]](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/). While El Niño typically influences seasonal precipitation patterns, it does not dictate specific daily weather outcomes or localized weather in mid-September [[1]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)[[5]](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/)[[13]](https://www.weather.gov/abq/clifeature_elninoprecip)[[14]](https://www.weather.gov/media/sgx/newsletter/current-newsletter.pdf).

San Francisco expects no significant rainfall in mid-September 2026. For the weekend of September 19-20, 2026, San Francisco is expected to experience negligible or no measurable rainfall [[6]](https://www.weathertab.com/en/c/09/united-states/california/san-francisco/)[[7]](https://en.climate-data.org/north-america/costa-rica/san-jose/san-francisco-555187/t/september-9/)[[8]](https://www.weathertab.com/en/long-range-weather/09/19/united-states/california/94130-san-francisco/)[[9]](https://www.easeweather.com/north-america/united-states/california/san-francisco/september). The city typically experiences very dry conditions in September, and current long-range and daily forecasts for the Bay Area show no significant precipitation, with conditions ranging from partly cloudy to mostly cloudy [[6]](https://www.weathertab.com/en/c/09/united-states/california/san-francisco/)[[7]](https://en.climate-data.org/north-america/costa-rica/san-jose/san-francisco-555187/t/september-9/)[[8]](https://www.weathertab.com/en/long-range-weather/09/19/united-states/california/94130-san-francisco/)[[9]](https://www.easeweather.com/north-america/united-states/california/san-francisco/september)[[15]](https://forecast.weather.gov/product.php?format=TXT&glossary=0&highlight=off&issuedby=MTR&product=SFT&site=NWS&version=26)[[16]](https://forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=MTR&product=SFT&site=NWS&version=26).

New Orleans has some rain potential, though conditions are trending drier. New Orleans, which typically has a humid and wet climate in September [[17]](https://bestdateweather.com/en/new-orleans-weather-september), has some indicated rain potential for the weekend of September 19-20, 2026. Forecast models show a **40%** chance of rain on September 19 due to scattered thunderstorms [[10]](https://www.easeweather.com/north-america/united-states/louisiana/orleans-parish/new-orleans/september)[[11]](https://www.wunderground.com/hourly/us/la/new-orleans/70130/date/2026-9-19). However, the short-term outlook for New Orleans indicates a drying trend, with rain chances decreasing to **15%** or less by early next week [[12]](https://www.weather.gov/lix).

Sources:

1. [Climate Prediction Center: ENSO Diagnostic Discussion - NOAA](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)
2. [Climate Prediction Center - Official NOAA CPC ENSO Probabilities](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/probabilities/)
3. [ENSO: Recent Evolution,](https://www.cpc.ncep.noaa.gov/products/analysis%5Fmonitoring/lanina/enso%5Fevolution-status-fcsts-web.pdf)
4. [September 2026 El Niño Predictions – Geophysical Fluid Dynamics Laboratory](https://www.gfdl.noaa.gov/prediction/september-2026-el-nino-predictions/)
5. [Climate Prediction Center - Outlooks](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/)
6. [September 2026 Daily Weather Forecast for San Francisco, California – Plan Ahead](https://www.weathertab.com/en/c/09/united-states/california/san-francisco/)
7. [Weather San Francisco in September 2026: Temperature & Climate](https://en.climate-data.org/north-america/costa-rica/san-jose/san-francisco-555187/t/september-9/)
8. [94130 (San Francisco), California Weather Forecast for September 19, 2026](https://www.weathertab.com/en/long-range-weather/09/19/united-states/california/94130-san-francisco/)
9. [September 2026 Weather - San Francisco](https://www.easeweather.com/north-america/united-states/california/san-francisco/september)
10. [September 2026 Weather - New Orleans](https://www.easeweather.com/north-america/united-states/louisiana/orleans-parish/new-orleans/september)
11. [New Orleans, LA Hourly Weather Forecast | Weather Underground](https://www.wunderground.com/hourly/us/la/new-orleans/70130/date/2026-9-19)
12. [New Orleans/Baton Rouge](https://www.weather.gov/lix)
13. [NWS ABQ - El Nino Precipitation](https://www.weather.gov/abq/clifeature_elninoprecip)
14. [Inside this issue:](https://www.weather.gov/media/sgx/newsletter/current-newsletter.pdf)
15. [National Weather Service](https://forecast.weather.gov/product.php?format=TXT&glossary=0&highlight=off&issuedby=MTR&product=SFT&site=NWS&version=26)
16. [National Weather Service](https://forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=MTR&product=SFT&site=NWS&version=26)
17. [New Orleans Weather in September 2026: what to expect (5.2/10)](https://bestdateweather.com/en/new-orleans-weather-september)

## What is the historical precipitation frequency for New York City versus Las Vegas for the third week of September, according to NOAA and NCEI data?

NYC Sept 3rd Week Rain Events | Regular measurable precipitation events [[1]](https://www.weather.gov/media/okx/Climate/Almanacs/nyc/nycsep.pdf)[[2]](https://www.weather.gov/media/vef/Las_Vegas_climate_book_September.pdf) |
Las Vegas Sept Normal Precipitation | Approximately 0.32 inches (monthly) [[3]](https://www.weather.gov/media/wrh/online_publications/TMs/TM-271.pdf) |
Las Vegas Sept Rain Frequency | Very low, with minimal days of measurable precipitation [[3]](https://www.weather.gov/media/wrh/online_publications/TMs/TM-271.pdf)[[4]](https://www.weather.gov/media/vef/Climate/Las%20Vegas%20Climate%20Book%20Temp/Precipitation%20Overview.pdf) |

**New York City historically experiences significantly higher September precipitation**

New York City historically experiences significantly higher September precipitation. Daily records for New York City, encompassing locations such as Central Park and LaGuardia, consistently show measurable precipitation events during the third week of September. These events often include notable historical storms, such as Tropical Cyclone Jose in 2017 [[1]](https://www.weather.gov/media/okx/Climate/Almanacs/nyc/nycsep.pdf)[[5]](https://www.weather.gov/media/okx/Climate/Almanacs/LGA/lgasep.pdf)[[2]](https://www.weather.gov/media/vef/Las_Vegas_climate_book_September.pdf).

In contrast, Las Vegas has a very low historical precipitation frequency. Its arid climate contributes to a minimal number of days with measurable precipitation (0.01 inches or more) in September. The region's monthly normal precipitation for September is approximately 0.32 inches [[3]](https://www.weather.gov/media/wrh/online_publications/TMs/TM-271.pdf)[[4]](https://www.weather.gov/media/vef/Climate/Las%20Vegas%20Climate%20Book%20Temp/Precipitation%20Overview.pdf). Therefore, during the third week of September, precipitation is significantly more frequent and intense in New York City than in Las Vegas [[1]](https://www.weather.gov/media/okx/Climate/Almanacs/nyc/nycsep.pdf)[[5]](https://www.weather.gov/media/okx/Climate/Almanacs/LGA/lgasep.pdf)[[4]](https://www.weather.gov/media/vef/Climate/Las%20Vegas%20Climate%20Book%20Temp/Precipitation%20Overview.pdf).

Sources:

1. [CENTRAL PARK NY SEPTEMBER ALMANAC](https://www.weather.gov/media/okx/Climate/Almanacs/nyc/nycsep.pdf)
2. [September Climate Data for Las Vegas](https://www.weather.gov/media/vef/Las_Vegas_climate_book_September.pdf)
3. [CLIMATE OF LAS VEGAS, NEVADA](https://www.weather.gov/media/wrh/online_publications/TMs/TM-271.pdf)
4. [Precipitation Overview](https://www.weather.gov/media/vef/Climate/Las%20Vegas%20Climate%20Book%20Temp/Precipitation%20Overview.pdf)
5. [LAGUARDIA NY SEPTEMBER ALMANAC](https://www.weather.gov/media/okx/Climate/Almanacs/LGA/lgasep.pdf)

## What do the final El Niño Southern Oscillation (ENSO) forecasts from the CPC and ECMWF for mid-September 2026 indicate for regional precipitation patterns across the United States?

El Niño Persistence Probability | Greater than 90% (through Northern Hemisphere fall and winter 2026-27) [[1]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf)[[2]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)[[3]](https://www.cpc.ncep.noaa.gov/products/Drought/briefing/current.pdf)[[4]](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/forecast-highlights.html) |
Eastern Equatorial Pacific SST Anomaly | Exceeded +3.0°C [[2]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)[[4]](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/forecast-highlights.html) |
Seasonal Precipitation Outlook | Above-normal precipitation (across much of the southern and central United States) [[3]](https://www.cpc.ncep.noaa.gov/products/Drought/briefing/current.pdf)[[5]](https://climateimpactcompany.com/september-2026-monthly-enso-outlook-ecmwf-precipitation-impacts-caused-by-super-el-nino-for-dec-jan-feb-2026-27-2-2/) |

**A very strong El Niño event is confirmed, projected to persist through winter**

A very strong El Niño event is confirmed, projected to persist through winter. As of mid-September 2026, a very strong El Niño is confirmed and expected to continue through the Northern Hemisphere fall and winter 2026-27 with a greater than **90%** **probability** [[1]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf)[[2]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)[[3]](https://www.cpc.ncep.noaa.gov/products/Drought/briefing/current.pdf)[[4]](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/forecast-highlights.html). This strengthening event is characterized by sea surface temperature anomalies in the eastern equatorial Pacific that have already surpassed +3.0°C [[2]](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)[[4]](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/forecast-highlights.html). General seasonal precipitation outlooks associated with this strong El Niño favor above-normal precipitation across much of the southern and central United States [[3]](https://www.cpc.ncep.noaa.gov/products/Drought/briefing/current.pdf)[[5]](https://climateimpactcompany.com/september-2026-monthly-enso-outlook-ecmwf-precipitation-impacts-caused-by-super-el-nino-for-dec-jan-feb-2026-27-2-2/).

Specific forecasts indicate varied regional precipitation patterns for September. For the weekend of September 19-20, 2026, the 6-10 day outlook forecasts a pattern transition [[6]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)[[7]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html). This includes enhanced moisture favoring above-normal precipitation across the Southwest [[6]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)[[7]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html). Above-normal precipitation is also anticipated from the Northeast and Mid-Atlantic towards the Middle Mississippi Valley due to a predicted frontal boundary [[6]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)[[7]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html). Conversely, cooler and drier conditions are expected for many areas east of the Rockies, and the Pacific Northwest is predicted to be drier than normal [[3]](https://www.cpc.ncep.noaa.gov/products/Drought/briefing/current.pdf)[[5]](https://climateimpactcompany.com/september-2026-monthly-enso-outlook-ecmwf-precipitation-impacts-caused-by-super-el-nino-for-dec-jan-feb-2026-27-2-2/)[[6]](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)[[7]](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html). Broader forecasts for September 2026 suggest recurrent, moderate wet signals rather than a single dominant, extreme rainfall event [[8]](https://pogodnik.com/en/news/usa-canada-weather-forecast-september-2026).

Sources:

1. [\[PDF\] ENSO: Recent Evolution, Current Status and Predictions](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf)
2. [Climate Prediction Center: ENSO Diagnostic Discussion - NOAA](https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)
3. [Drought Outlook Support Briefing](https://www.cpc.ncep.noaa.gov/products/Drought/briefing/current.pdf)
4. [EL NINO /SOUTHERN OSCILLATION (ENSO)](https://www.cpc.ncep.noaa.gov/products/CDB/Forecast/forecast-highlights.html)
5. [ECMWF El Nino-Driven Precipitation Impacts Caused by Super El Nino for DEC/JAN/FEB 2026-27 - Climate Impact Company](https://climateimpactcompany.com/september-2026-monthly-enso-outlook-ecmwf-precipitation-impacts-caused-by-super-el-nino-for-dec-jan-feb-2026-27-2-2/)
6. [Probabilistic Hazards Outlook](https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php)
7. [Climate Prediction Center - 6-10 and 8-14 Day Prognostic Discussions](https://www.cpc.ncep.noaa.gov/products/predictions/6-10_day/fxus06.html)
8. [USA & Canada Weather Forecast September 2026: Heat, Rain...](https://pogodnik.com/en/news/usa-canada-weather-forecast-september-2026)

## What Could Change the Odds

**The National Weather Service Storm Prediction Center reported on September 16, 2026, that severe weather potential for September 19-20, 2026, is extremely low or marginal across the United States [[1]](https://www.severeweatheroutlook.com/2026-09-20/)[[2]](https://www.severeweatheroutlook.com/2026-09-19/).** As of mid-August 2026, the long-range weather outlook for the weekend of September 19-20, 2026, indicated generally unsettled conditions across parts of the Northeast, with specific rainfall predictions having low **confidence** and remaining subject to change [[3]](https://preview-forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=ALY&product=AFD&site=IND&version=20)[[4]](https://forecast.weather.gov/product.php?format=TXT&glossary=1&highlight=off&issuedby=BUF&product=AFD&site=NWS&version=19).

**Global climate trends for the July-September 2026 season feature heightened probabilities for above-normal rainfall across the central and eastern equatorial Pacific, influenced by an ongoing strong El Niño event [[5]](https://precip.earth/)[[6]](https://precip.earth/forecast)[[7]](https://public.wmo.int/media/update/global-seasonal-climate-update-july-august-september-2026).** Other regions, including the Greater Horn of Africa, parts of Central America, and the Caribbean, face increased likelihoods of below-normal precipitation during this period [[5]](https://precip.earth/)[[6]](https://precip.earth/forecast)[[7]](https://public.wmo.int/media/update/global-seasonal-climate-update-july-august-september-2026). September 19, 2026, serves as a specific resolution date for several prediction **market** events, such as topics related to OpenAI's Astra **model** release, geopolitical tensions, and Elon Musk's tweet counts [[8]](https://predictparity.com/markets/p/will-openais-astra-model-be-released-on-september-19-2026/yes)[[9]](https://predictparity.com/markets/p/will-russia-target-kyiv-on-september-19-2026)[[10]](https://polymarket.com/event/elon-musk-of-tweets-september-17-september-19-2026).

Sources:

1. [Outlook for Sunday, September 20 | Severe Weather Outlook](https://www.severeweatheroutlook.com/2026-09-20/)
2. [Outlook for Saturday, September 19 | Severe Weather Outlook](https://www.severeweatheroutlook.com/2026-09-19/)
3. [National Weather Service](https://preview-forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=ALY&product=AFD&site=IND&version=20)
4. [National Weather Service](https://forecast.weather.gov/product.php?format=TXT&glossary=1&highlight=off&issuedby=BUF&product=AFD&site=NWS&version=19)
5. [precip.earth — the planet's rain, snow, floods and drought](https://precip.earth/)
6. [Rain forecast, next 15 days — ECMWF ensemble | precip.earth](https://precip.earth/forecast)
7. [Global Seasonal Climate Update for July-August-September 2026](https://public.wmo.int/media/update/global-seasonal-climate-update-july-august-september-2026)
8. [Will OpenAI's Astra model be released on September 19, 2026? | Parity](https://predictparity.com/markets/p/will-openais-astra-model-be-released-on-september-19-2026/yes)
9. [Will Russia target Kyiv on September 19, 2026? | Parity](https://predictparity.com/markets/p/will-russia-target-kyiv-on-september-19-2026)
10. [Elon Musk # tweets September 17 - September 19, 2026?](https://polymarket.com/event/elon-musk-of-tweets-september-17-september-19-2026)

## Key Dates & Catalysts

- **Expiration:** September 23, 2026
- **Closes:** September 21, 2026

## Decision-Flipping Events

- The National Weather Service Storm Prediction Center reported on September 16, 2026, that severe weather potential for September 19-20, 2026, is extremely low or marginal across the United States [[1]](https://www.severeweatheroutlook.com/2026-09-20/)[[2]](https://www.severeweatheroutlook.com/2026-09-19/).
- As of mid-August 2026, the long-range weather outlook for the weekend of September 19-20, 2026, indicated generally unsettled conditions across parts of the Northeast, with specific rainfall predictions having low **confidence** and remaining subject to change [[3]](https://preview-forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=ALY&product=AFD&site=IND&version=20)[[4]](https://forecast.weather.gov/product.php?format=TXT&glossary=1&highlight=off&issuedby=BUF&product=AFD&site=NWS&version=19).
- Global climate trends for the July-September 2026 season feature heightened probabilities for above-normal rainfall across the central and eastern equatorial Pacific, influenced by an ongoing strong El Niño event [[5]](https://precip.earth/)[[6]](https://precip.earth/forecast)[[7]](https://public.wmo.int/media/update/global-seasonal-climate-update-july-august-september-2026).
- Other regions, including the Greater Horn of Africa, parts of Central America, and the Caribbean, face increased likelihoods of below-normal precipitation during this period [[5]](https://precip.earth/)[[6]](https://precip.earth/forecast)[[7]](https://public.wmo.int/media/update/global-seasonal-climate-update-july-august-september-2026).

Sources:

1. [Outlook for Sunday, September 20 | Severe Weather Outlook](https://www.severeweatheroutlook.com/2026-09-20/)
2. [Outlook for Saturday, September 19 | Severe Weather Outlook](https://www.severeweatheroutlook.com/2026-09-19/)
3. [National Weather Service](https://preview-forecast.weather.gov/product.php?format=TXT&glossary=0&issuedby=ALY&product=AFD&site=IND&version=20)
4. [National Weather Service](https://forecast.weather.gov/product.php?format=TXT&glossary=1&highlight=off&issuedby=BUF&product=AFD&site=NWS&version=19)
5. [precip.earth — the planet's rain, snow, floods and drought](https://precip.earth/)
6. [Rain forecast, next 15 days — ECMWF ensemble | precip.earth](https://precip.earth/forecast)
7. [Global Seasonal Climate Update for July-August-September 2026](https://public.wmo.int/media/update/global-seasonal-climate-update-july-august-september-2026)

## Related Research Reports

- [EU meets its 2030 climate goals?](/markets/climate-and-weather/climate-change/eu-meets-its-2030-climate-goals/)
- [EV market share in 2030?](/markets/climate-and-weather/energy/ev-market-share-in-2030/)
- [Consecutive days of average temperature in Oklahoma City above 90°F - week of Aug 18, 2026](/markets/climate-and-weather/heatwaves/consecutive-days-of-average-temperature-in-oklahoma-city-above-90-f-week-of-aug-18-2026/)
- [Will there be an at least 8.0 magnitude earthquake in California before 2028?](/markets/climate-and-weather/will-there-be-an-at-least-8-0-magnitude-earthquake-in-california-before-2028/)

## Historical Resolutions

**Historical Resolutions:** 20 markets in this series

**Outcomes:** 10 resolved YES, 10 resolved NO

**Recent resolutions:**

- KXRAINWKND-26SEP12-WPB: YES (Sep 14, 2026)
- KXRAINWKND-26SEP12-TTN: YES (Sep 14, 2026)
- KXRAINWKND-26SEP12-SFO: NO (Sep 14, 2026)
- KXRAINWKND-26SEP12-SEA: YES (Sep 14, 2026)
- KXRAINWKND-26SEP12-SATX: NO (Sep 14, 2026)

## Disclaimer

This content is for informational and educational purposes only and does not constitute financial, investment, legal, or trading advice.
Prediction markets involve risk of loss. Past performance does not guarantee future results.
We are not affiliated with Kalshi or any prediction market platform. Market data may be delayed or incomplete.

### Data Sources & Model Transparency

**Data Sources:** Octagon Deep Research aggregates information from multiple sources including news, filings, and market data.

**Freshness:** Analysis is generated periodically and may not reflect the latest developments. Verify critical information from primary sources.

## Attribution Policy

When quoting, summarizing, or reproducing Octagon content, attribute it to Octagon and link to the Octagon source URL: https://www.octagonai.co/markets/climate-and-weather/snow-and-rain/where-will-it-rain-this-weekend-sep-19-sep-20
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