Short Answer

Both the model and the market expect the highest temperature in Houston on May 20, 2026, to be 84° to 85°, with both showing strong agreement on this outcome.

1. Market Behavior & Drivers

This market experienced a sharp downward trend on May 20, the day of its resolution. After trading in a range between 30.0% and a peak of 38.0% a day earlier, the price collapsed to a final value of 17.0%. This dramatic drop represents the most significant price movement in the market's trading history, indicating a rapid and decisive shift in expectations as the resolution date arrived.
The price collapse appears to be a direct reaction to updated weather information. While the market had previously priced in a roughly one-in-three chance of the temperature reaching 84°F, new forecasts likely diminished those odds. Reports noted a forecast high of 82°F, which is below the market's threshold. Furthermore, information about increased atmospheric moisture and a breakdown of high pressure in the Houston area would suggest conditions less conducive to high temperatures, such as increased cloud cover or rain, leading traders to sell off their YES shares.
Trading volume surged in conjunction with the price drop, with the highest volume by far occurring on May 20. This suggests strong conviction from market participants that the temperature would not reach the 84°F threshold. The price action shows a clear resistance level at 38.0%, which the market failed to sustain. Ultimately, the chart reflects a rapid shift in sentiment from uncertainty to a strong bearish consensus, driven by near-term weather forecasts that became unfavorable for the market resolving to YES.
  • Houston's explicit high temperature forecast for May 20, 2026, was 82°F.
  • Expected heavy rainfall likely suppresses daily high temperatures several degrees below average.
  • Normal May high temperatures for Houston are approximately 86°F–87°F.
  • Long-range climate outlooks suggested above-normal temperatures for southern North America.
  • Historical record high for May 20 is 95°F, though current conditions oppose it.

Current Context

Houston's forecast high temperature for May 20, 2026, was 82°F [1]. This predicted value was significantly below the historical record high for Houston on May 20, which was 95°F, established in 2008 [2].
Local weather patterns indicated increased moisture and flood risk. Around May 20, 2026, the Houston area experienced a breakdown of high pressure and elevated atmospheric moisture [3][4][5]. These conditions led to the issuance of a Stage 2 flood alert due to the potential for heavy rainfall [3][4][5].
Prediction markets tracked various temperature thresholds for the day. Platforms such as Robinhood hosted events specifically monitoring the daily high temperature in Houston for May 20, 2026 [6]. These markets included options for achieving high temperatures of 82°F, 83°F, and 84°F [6].
Sources (6)
  1. 1Weather in Houston in May 2026 (Texas) - Detailed Weather Forecast for a Monthworld-weather.info
  2. 2Houston May 20 Weather Recordsextremeweatherwatch.com
  3. 3With multiple days of heavy rainfall possible, we are initiating a Stage 2 flood alert through the weekendspacecityweather.com
  4. 4May 2026 – Space City Weatherspacecityweather.com
  5. 5This week's forecastkingwood.com
  6. 6Houston Daily Temperature High May 20 2026 - Robinhoodrobinhood.com

2. Price Chart

Historical Price (Probability)

Outcome probability
Date

3. Market Data

Contract Snapshot

This contract resolves to "Yes" if the maximum temperature recorded in Houston on May 20, 2026, is between 84-85°F, according to the National Weather Service's Climatological Report (Daily); otherwise, it resolves to "No." Trading concludes at 11:59 PM local time on May 20, 2026, with the market expiring by the earlier of various conditions related to data release or one week after, and payouts projected 30 minutes post-closing. Settlement relies solely on the official NWS Climatological Report for Houston-Hobby, TX, available via weather.gov, with a caution that preliminary data may have rounding nuances.

Market Discussion

Prediction markets, such as Polymarket, assigned a 30% probability to the 82-83°F range for Houston's highest temperature on May 20, 2026 [1]. This temperature expectation was influenced by a wet and unsettled weather pattern in Houston leading up to and including that date, characterized by a Stage 2 flood alert, heavy rainfall, and high humidity [2][3][4].

Sources (4)
  1. 1Highest temperature in Houston on May 20? - Polymarketpolymarket.com
  2. 2With multiple days of heavy rainfall possible, we are initiating a Stage 2 flood alert through the weekendspacecityweather.com
  3. 3Houston Expects Heavy Rainfall Through Memorial Day with Potential for Severe Weather and Power Outagestime.news
  4. 4This week's forecastkingwood.com

4. What are the prevailing ENSO (El Niño-Southern Oscillation) forecasts for Spring 2026, and how have past El Niño vs. La Niña cycles historically impacted May temperatures in Houston?

El Niño Probability (May-July 2026)82% [1][2][3]
ENSO Status (May 20, 2026)Rapid transition from ENSO-neutral to El Niño [1][2][3]
Houston Summer Temp & ENSO CorrelationNot strong or consistent [4]
El Niño is likely to emerge by summer 2026. As of May 20, 2026, the equatorial Pacific is undergoing a rapid transition from ENSO-neutral to El Niño conditions. Forecasters indicate an 82% probability that El Niño will emerge during the May–July 2026 period [1][2][3].
ENSO phases do not strongly correlate with Houston's summer temperatures. Extreme heat events in Houston have occurred during both El Niño and La Niña years, indicating no strong, consistent relationship [4]. Instead, local summer heat is more closely linked to factors such as persistent high-pressure systems, soil moisture, and overnight temperatures [4]. The normal high temperature for Houston in May ranges from approximately 86°F to 87°F, with historical record highs for May 20th reaching into the mid-to-upper 90s [5][6].
Sources (6)
  1. 1Climate Prediction Center: ENSO Diagnostic Discussioncpc.ncep.noaa.gov
  2. 2IRI – International Research Institute for Climate and Society | May 2026 Quick Lookiri.columbia.edu
  3. 3El Niño to arrive in weeks, not months. What does it mean for Texas and hurricane season?msn.com
  4. 4How a more likely Super El Niño could affect Texas hurricane seasonhoustonchronicle.com
  5. 5Houston HOU Normals/Means/Extremes - Mayweather.gov
  6. 6National Weather Serviceforecast.weather.gov

5. What specific short-term weather patterns, such as a 'heat dome' or a Gulf of Mexico disturbance, would need to materialize in the week of May 20, 2026, to challenge the historical record of 95°F?

Houston May 20 Record High95°F (set in 2008) [1]
Primary Weather Pattern NeededPersistent, strong high-pressure ridge or "heat dome" [2]
Moisture Condition for RecordSubstantial moisture plume, capped to allow strong daytime warming [3]
Challenging Houston's May 20 temperature record requires a specific atmospheric setup. To surpass the city's all-time record high of 95°F for May 20, which was established in 2008, a persistent and strong high-pressure ridge, commonly known as a "heat dome," must materialize [2]. This weather pattern typically brings mostly sunny conditions and near-zero chances of precipitation. While temperatures under such a dome commonly range from the mid- to upper-80s, occasional days might reach approximately 90°F over the course of about a week [2]. For the historical record to be threatened, daily maximum temperatures would need to consistently be at or above 95°F [1].
A Gulf of Mexico moisture plume is also essential for record heat. Alongside the heat dome, a substantial moisture plume originating from the Gulf of Mexico and extending across Texas into Central America is necessary [3]. Although such a moisture plume usually indicates a potential for widespread rainfall, for the 95°F record to be broken on May 20, this moisture would need to increase humidity while remaining either capped or sufficiently spotty [3]. This precise condition is critical to facilitate robust daytime surface warming, rather than being moderated by widespread convective activity, thereby allowing temperatures to ascend to record-challenging levels [3].
Sources (3)
  1. 1Houston May 20 Weather Recordsextremeweatherwatch.com
  2. 2A massively strong high pressure system over the Western US will extend its influence to Texas – Space City Weatherspacecityweather.com
  3. 3May 2026 – Space City Weatherspacecityweather.com

6. Given the potential for heavy rainfall, what is the typical impact of significant rain events on daily high temperatures in Houston during late May, according to historical weather data?

Average Late May High Temp86-870F (30-310C) [1][2][3]
Record High Temp (May 20)950F (350C) in 2008 [4][1][5][6]
Rain Event Impact on TempSeveral degrees below seasonal average [4][3]
Late May in Houston typically sees high temperatures around 86-87°F. Average daily high temperatures in Houston during late May are generally around 86-87°F (30-31°C) [1][2][3]. Historically, the record high for May 20 was 95°F (35°C), which occurred in 2008 [4][1][5][6]. Specific temperature predictions for May 20, 2026, are not available from the provided information.
Heavy rainfall often lowers Houston's daily high temperatures. Significant rain events in late May can cause Houston's daily high temperatures to be several degrees lower than the typical seasonal average [4][3]. This reduction in temperature is primarily due to increased cloud cover and the cooling effect that evaporation provides [4][3].
Sources (6)
  1. 1Houston May Weatherextremeweatherwatch.com
  2. 2Houston IAH Extremes, Normals, and Annual Summariesweather.gov
  3. 3Climate of Houstonen.wikipedia.org
  4. 4Houston IAH Normals/Means/Extremes - Mayweather.gov
  5. 5Houston May 20 Weather Recordsextremeweatherwatch.com
  6. 6IEM:: CLI from NWS HGXmesonet.agron.iastate.edu

7. What are the most reliable public datasets for tracking Gulf of Mexico sea surface temperatures and regional soil moisture levels, and what do current 2026 trends in these datasets suggest for summer temperatures in Houston?

Primary GoM SST Data SourceNOAA's 1/4° Daily Optimum Interpolation Sea Surface Temperature (OISST) [1]
Primary Houston Soil Moisture Data SourceNASA's Soil Moisture Active Passive (SMAP) L4 gridded products [2]
Houston Forecast Highs (May 2026)Upper 80s to 90°F [3]
Reliable public datasets track Gulf of Mexico temperatures and Houston soil moisture. For Gulf of Mexico sea surface temperatures (SST), trusted sources include NOAA's 1/4° Daily Optimum Interpolation Sea Surface Temperature (OISST) [1] and NOAA CoastWatch's high-resolution satellite-based products, such as VIIRS-based L4 analyses [4][5][6]. Regional soil moisture levels in the Houston area can be monitored through NASA's Soil Moisture Active Passive (SMAP) L4 gridded products, the Texas Soil Observation Network (TxSON), and local networks like those operated by the Harris County Flood Control District (HCFCD) [2][7][8].
May 2026 forecasts offer limited insight into summer trends. As of May 15, 2026, Houston's weather forecast indicated a shift towards a more active and humid weather pattern. Daytime temperatures were generally predicted to be in the upper 80s to 90°F range, with no immediate extreme heat waves expected for the week of May 20, 2026 [3]. However, current 2026 trends for either Gulf of Mexico sea surface temperatures or regional soil moisture datasets are not available within the provided information. Consequently, there is no data to infer what these trends might imply for Houston's summer temperatures.
Sources (8)
  1. 1Optimum Interpolation Sea Surface Temperature (OISST) | National Centers for Environmental Information (NCEI)ncei.noaa.gov
  2. 2Soil Moisture Monitoring in Houstontceq.texas.gov
  3. 3May 2026 – Space City Weatherspacecityweather.com
  4. 4Index.phpaoml.noaa.gov
  5. 5Sea Surface Temperature | NOAA CoastWatchcoastwatch.noaa.gov
  6. 6Coastal Water Temperature Guide | National Centers for Environmental Information (NCEI)ncei.noaa.gov
  7. 7https://www.osti.gov/servlets/purl/1974568osti.gov
  8. 8Drought and Soil Moisture Data | Drought.govdrought.gov

8. How do long-range climate outlooks from the Climate Prediction Center (CPC) and the European Centre for Medium-Range Weather Forecasts (ECMWF) for May 2026 compare in their temperature anomaly predictions for Southeast Texas?

CPC late May 2026 temp outlookEqual chances (EC) of above- or below-normal temperatures for south-central U.S. [1]
Global May-Jul 2026 temp outlookStrong tilt toward above-normal temperatures for southern North America [2]
Private Sector Summer 2026 outlookRisks of anomalous heat for Gulf States [3]
Long-range climate outlooks for May 2026 offered differing temperature anomaly predictions for regions including Southeast Texas. The Climate Prediction Center (CPC) outlooks for the latter part of May 2026 indicated "equal chances" (EC) of above- or below-normal temperatures for the south-central United States [1]. These CPC outlooks also highlighted a potential for enhanced precipitation and associated flooding risks within Southeast Texas, a factor that influenced the overall temperature forecast [1][4].
Conversely, other outlooks indicated a strong tilt towards warmer temperatures. Global seasonal climate updates for the May-June-July 2026 period, which integrate multi-model ensembles including the European Centre for Medium-Range Weather Forecasts (ECMWF), projected a strong and consistent tendency for above-normal land surface temperatures across much of the mid-latitudes, specifically encompassing southern North America [2]. Furthermore, private sector outlooks extending into summer 2026 suggested that the Gulf States, including Texas, faced risks of anomalous heat, particularly if the forecasted precipitation did not materialize as anticipated [3].
Sources (4)
  1. 1Climate Prediction Center - Week 3-4 Outlookcpc.ncep.noaa.gov
  2. 2Global Seasonal Climate Update for May-June-July 2026wmo.int
  3. 3Updated Summer 2026 Outlook: Hot Northwest/West and Gulf States; Wet Midwest; Late Summer Drought Mid-south/Texas - Climate Impact Companyclimateimpactcompany.com
  4. 4Probabilistic Hazards Outlookcpc.ncep.noaa.gov

9. What Could Change the Odds

Key Catalysts

Key prediction market catalysts in May 2026 include the May US inflation report, which is scheduled for June 10 [1]. Additionally, a Trump-Xi summit announcement has a deadline of May 22 [2].
There are also ongoing bets regarding a potential US-Iran peace deal, with resolution dates in May and June 2026 [3]. Furthermore, Federal Reserve interest rate cut expectations are also considered key catalysts [4].

Key Dates & Catalysts

  • Strike Date: May 21, 2026
  • Expiration: May 27, 2026
  • Closes: May 21, 2026
Sources (4)
  1. 1May Inflation US - Monthly Trading Odds & Predictions 2026 | Polymarketpolymarket.com
  2. 2Trump-Xi Summit: What will Trump announce by May 22? Pred... 2026 | Polymarketpolymarket.com
  3. 3Predicting Peace: Iran Deal Betsstartuphub.ai
  4. 4Markets Drop Fed Rate Cut Bets for 2026ts2.tech

11. Historical Resolutions

Historical Resolutions: 20 markets in this series

Outcomes: 3 resolved YES, 17 resolved NO

Recent resolutions:

  • KXHIGHTHOU-26MAY18-T93: NO (May 19, 2026)
  • KXHIGHTHOU-26MAY18-T86: NO (May 19, 2026)
  • KXHIGHTHOU-26MAY18-B92.5: NO (May 19, 2026)
  • KXHIGHTHOU-26MAY18-B90.5: NO (May 19, 2026)
  • KXHIGHTHOU-26MAY18-B88.5: NO (May 19, 2026)