Short Answer

Both the model and the market expect 'Hottest' as the most likely outcome for 2026, with no compelling evidence of mispricing.

1. Market Behavior & Drivers

This prediction market has exhibited a sideways trading pattern, contained within a narrow range between approximately 29% and 34%. The price started at 29.1% and currently sits at 30.2%, indicating very little net change over the period. The most significant movement was a price spike to a high of 33.6% around April 29th. This brief surge in perceived probability directly corresponds with the timing of a blog post by scientist James Hansen, who explicitly inferred that 2026 would likely be the warmest year on record. Following this peak, the price has since retreated, suggesting the market's initial bullish reaction was not sustained.
The total volume of over 14,500 contracts indicates significant initial interest, but the recent sample data points show very low to zero volume, suggesting a current lack of conviction or a wait-and-see approach from traders. The 29% level appears to be acting as a support floor, while the peak near 34% has established a clear resistance ceiling. Overall, the market sentiment, reflected by the current price of 30.2%, is cautiously pessimistic about 2026 setting a new temperature record. This probability aligns more closely with the nuanced forecasts from organizations like Carbon Brief (19% chance) and the Met Office, rather than the more definitive prediction from Hansen. The price action suggests that while traders reacted to Hansen's forecast, the broader consensus from other climate organizations is keeping the probability from rising further.
  • A strong El Niño in late 2026 is required for a new record.
  • Mid-2026 developing El Niño conditions contrast with 2024's decline.
  • NASA GISTEMP v4 is the primary dataset for 2026 global temperature.
  • Agencies like the Met Office forecast 2026 as likely second-warmest.
  • A major volcanic eruption could prevent 2026 from setting a record.

Who Wins and Why

Outcome Market Model Why
Hottest 30.2% 22.1% The accelerating pace of global warming makes record-breaking temperatures increasingly probable.

Current Context

Experts anticipate 2026 to be exceptionally warm, though records remain uncertain. As of May 6, 2026, Carbon Brief, which synthesizes multiple datasets and expert analyses, indicates that 2026 is likely to be the second-warmest year on record, with a 19% probability of surpassing 2024's record for the warmest year. It also notes that a strong El Niño developing late in 2026 could shift the highest chance of a new record to 2027 [1]. The Met Office's 2026 outlook forecasts a central global mean temperature of 1.46°C above the 1850–1900 average, with a range of 1.34–1.58°C. This outlook positions 2026 as likely one of the four warmest years, potentially just behind 2024 (1.55°C), with the possibility of reaching 1.5°C again [2]. Conversely, James Hansen's blog on April 30, 2026, explicitly infers that 2026 is likely to be the warmest year in the instrumental temperature record, while acknowledging that analysts often avoid confident predictions due to the substantial warmth required in remaining months to exceed the 2024 record [3].
Intensifying El Niño conditions are projected to significantly influence 2026 temperatures. The World Meteorological Organization (WMO) reports an increasing likelihood of El Niño emerging into the boreal summer and autumn. While ENSO-neutral conditions are most likely through spring, El Niño probabilities are rising into May–July, with El Niño expected to emerge from mid-2026 [4][5]. The WMO’s May–June–July 2026 seasonal climate update further supports this, indicating extreme or very high probabilities of above-normal sea-surface temperatures in the equatorial Pacific. This update also highlights a nearly global dominance of above-normal land surface temperatures, consistent with a rapid intensification of El Niño [6].
Prediction markets indicate high confidence in monthly, but not annual, records. In early February 2026, Polymarket's "will any month of 2026 be the hottest on record" market showed an approximate 75% implied probability for "Yes" based on crowd consensus [7]. This underscores an expectation within prediction markets for at least some month-level record heat during 2026, even if the prospect of the entire year being the warmest on record remains less certain.
Sources (7)
  1. 1State of the climate: Strong El Niño puts 2026 on track for second-warmest yearcarbonbrief.org
  2. 22026 outlook: likely another year above 1.4°C - Met Officemetoffice.gov.uk
  3. 32026 On Track for Warmest Year - by James Hansenjimehansen.substack.com
  4. 4WMO: Likelihood increases of El Niñowmo.int
  5. 5El Niño/La Niña Update (February 2026)wmo.int
  6. 6Global Seasonal Climate Update for May-June-July 2026wmo.int
  7. 7Will any month of 2026 be the hottest on record? Predicti... | Polymarketpolymarket.com

2. Price Chart

Historical Price (Probability)

Outcome probability
Date

3. Market Data

Contract Snapshot

The market resolves to "Yes" if the unsmoothed Land-Ocean Temperature Index for 2026, reported by NASA's Goddard Institute for Space Studies (GISS), is above both the 2025 value and 1.28 degrees Celsius; otherwise, it resolves to "No." The market closes on December 31, 2026, at 11:59 PM ET. It will expire at the sooner of 10:00 AM ET following the release of the 2026 data or 10:00 AM ET on April 1, 2027, with the outcome verified directly from NASA GISS data.

Available Contracts

Market options and current pricing

Outcome bucket Yes (price) No (price) Last trade probability
Hottest $0.30 $0.70 30%

Market Discussion

The market currently leans against 2026 being the hottest year ever, with a 69.6% chance for "No." Arguments for "Yes" primarily cite the potential for a strong and rapidly intensifying El Niño event, alongside the observed long-term trend of consecutive record-breaking warm years. Conversely, "No" proponents acknowledge 2026 will likely be one of the hottest on record but express doubt that an El Niño, if it returns, will be sufficient to surpass previous records and become the hottest.

4. Trust Index

Octagon Trust Index Kalshi 85 Strong
How it adds up
Integrity80% of score90Strong
Trade quality20% of score66Caution

Includes the cost to trade: a $1,000 order can't be filled here because the order book is too thin.

Trust score85Strong

Weighted blend with hard caps — a critically weak safety pillar, or a severe trading anomaly, caps the total regardless of the rest. Full methodology · About the Trust Index

Trust profile
Integrity4 screens run · 5 don't apply · 1 awaiting data
Market integrity
93Strong

Outcome is hard to influence

No suspicious activity on any screen

Screened clean
Large tradesNo single trade dominates the tape. Clear
Thin-volume movesNo significant move Clear
Size patternsNo distribution read Clear
2 screens not run
Outcome control · doesn't apply to this market type
Thin-leg conviction · doesn't apply to this market type
Info fairness
85Strong

No privileged early knowledge

No suspicious activity on any screen

Screened clean
Information exposureNo concentrated group can know the outcome materially early. Clear
4 screens not run
Move vs. catalyst · doesn't apply to this market type
Longshot repricing · doesn't apply to this market type
Pre-broadcast certainty · doesn't apply to this market type
Cross-venue timing · data source not connected
Resolution quality
92Strong

Resolution mechanism is dependable

No suspicious activity on any screen

Resolution rules read: Clear

Liquidity
84Deep

Size fills near the screen price

1 contract

Hottest84
Deep · low confidence

Light recent trading — size may not fill near the screen price.

Book spread 3% vs realized 1%
Move quality
70Stable

No significant moves

1 contract

Hottest—
No significant move (6h)

Price was stable over the last 6 hours.

Rule clarity
100Clear

Counts toward Resolution quality, not here

1 contract

Hottest100
Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Trade quality
66Caution

Order book is thin

Tradable, but expect execution cost beyond small sizes.

Outcome quality 84 (notional-weighted)

$100 order: 1.6c slippage (~2% of a 71.8c contract)

$1,000 order: book too thin to fill

$10,000 order: book too thin to fill

Hottest84Market scoreLiquidity84Move quality–Rule clarity100
Why 84
Liquidity
84 · Deep · low confidence

Light recent trading — size may not fill near the screen price.

Book spread 3% vs realized 1%
Move quality
No significant move (6h)

Price was stable over the last 6 hours.

Rule clarity
100 · Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear

underwriting_v1.4 · computed Sep 23, 2026

5. What specific El Niño strength and timing scenarios for late 2026 are required to push the year's average temperature past the 2024 record?

Peak Niño3.4 Anomaly for Recordaround 2.7°C [1]
Global Temperature Response Lagapproximately three months [2]
Chance of 2026 Surpassing 2024 Recordabout 19% [2]
A strong El Niño in late 2026 could set a new record. To push the 2026 calendar-year average temperature past the 2024 warmest-year record, a strong, potentially super, El Niño is required [2]. This specific scenario involves the Niño3.4 peak occurring in the latter part of 2026, with the maximum global surface temperature response lagging these peak conditions by approximately three months [2].
A super-El Niño peaking late is critical for a 2026 record. The "upper end" strength for such an outcome is a super-El Niño-like event, characterized by a multi-model median projection of a Niño3.4 peak anomaly around 2.7°C [1]. This event would need to develop in the latter part of 2026, as El Niño conditions typically peak towards the end of the year, with their maximum influence usually felt between November and February [3]. Consequently, the strongest conditions would need to manifest late enough in 2026 to significantly impact the October to December portion of the annual mean, consistent with the approximate three-month temperature response lag [3][2].
While challenging, this scenario has a measurable chance and carries future implications. One synthesis indicates that while this scenario is possible, it is not considered the baseline [2]. There is approximately a 19% chance of 2026 surpassing 2024 as the warmest year [2]. Furthermore, this specific strength and timing scenario for late 2026 would also have implications for 2027 being an extremely warm year [1].
Sources (3)
  1. 1Higher warming predictions for 2026 and 2027theclimatebrink.com
  2. 2State of the climate: Strong El Niño puts 2026 on track for second-warmest year - Carbon Briefcarbonbrief.org
  3. 3Pacific Ocean warming signals the possible return of a strong El Niño - Met Officemetoffice.gov.uk

6. How do the developing ENSO conditions and sea surface temperature anomalies in mid-2026 compare to the same period in 2024?

Probability of El Niño (May-July 2026)61-62% [1][2][3][4]
Niño 3.4 SST Anomaly (May 2026)+0.9°C [5]
2026 Global Mean Surface Temperature1.44  0.09 °C above pre-industrial levels [6]
Mid-2026 shows developing El Niño conditions, contrasting with 2024's decline. As of May 2026, ENSO-neutral conditions are present, with a high probability (61-62%) of transitioning to an El Niño event between May and July 2026, which is then expected to persist through the end of the year [1][2][3][4]. Some forecasts even indicate a 1-in-4 chance of a "super El Niño" by year-end, influenced by an unusual annular warming pattern in the tropical Pacific [4][7]. Early signs of this development include the Niño 3.4 sea surface temperature anomaly already reaching +0.9°C, signaling entry into El Niño territory, and a powerful subsurface oceanic Kelvin wave nearly 8°C above normal contributing to rapid intensification [4][5]. In contrast, mid-2024 experienced a diminishing El Niño event that transitioned to ENSO-neutral conditions, with increasing odds of a La Niña developing [8].
Global temperatures in 2026 are expected to be high, but likely not record-breaking. Global land and sea temperatures are widely forecast to be above normal for 2026 [2][4], with Environment and Climate Change Canada (ECCC) predicting a global mean surface temperature of 1.44 ± 0.09 °C above pre-industrial levels [6]. While 2026 is anticipated to be among the four hottest years on record, many climate outlooks suggest a low probability of it surpassing the 2024 record, which was the hottest ever recorded [6][9][10][11][12]. Many predictions suggest that the full warming impact of a late-2026 El Niño might be more pronounced in 2027, potentially making it a more likely candidate for a new record hottest year than 2026 [6][9][13][11].
Sources (13)
  1. 1noaa.govcpc.ncep.noaa.gov
  2. 2wmo.int
  3. 3noaa.govcpc.ncep.noaa.gov
  4. 4substack.combkobog.substack.com
  5. 5reddit.com
  6. 6climatedata.ca
  7. 7eurekalert.org
  8. 8weather.gov
  9. 9theclimatebrink.com
  10. 10theguardian.com
  11. 11reddit.com
  12. 12youtube.com
  13. 13columbia.edu

7. Which primary global temperature datasets, such as GISTEMP and HadCRUT, will be the key arbiters for the 2026 record, and what are their historical differences?

Primary Resolution Data Source (2026 Prediction Market)NASA GISTEMP [1]
GISTEMP v4 Data SourcesNOAA GHCN v4 (land) and ERSST v5 (ocean) [2][3]
HadCRUT5 ComponentsCRUTEM5 (land) and HadSST4 (sea-surface) [4][5]
NASA GISTEMP is the primary dataset for 2026 global temperature predictions. NASA GISTEMP v4 provides an estimate of global surface temperature change, using data from NOAA GHCN v4 stations for land areas and ERSST v5 for sea surface temperatures [2][3]. For the 2026 prediction market, GISTEMP's Land-Ocean Temperature Index table values are explicitly designated as the primary data source for resolution [1].
HadCRUT5 is another significant global temperature dataset with unique features. This gridded dataset compiles global historical surface temperature anomalies by combining CRUTEM5 for land surface air temperatures and HadSST4 for sea-surface temperatures [4][5]. HadCRUT5 is available in a non-infilled version, which contains coverage gaps, and an infilled "analysis" version. The infilled version employs a statistical approach to extend coverage in data-sparse regions and includes an ensemble of 200 realizations to quantify uncertainty [4][5][6][7][8].
Different data handling methods can cause shifts in temperature rankings. While the HadCRUT5 analysis version shows very close agreement with other estimates, such as NASA GISTEMP and Berkeley Earth, variations in how data gaps are addressed and uncertainty is treated can lead to differences in absolute rankings or recent trends [9]. This inherent variability is why multiple datasets are often considered when making claims about temperature records, though NASA GISTEMP remains the designated primary source for the 2026 market [9][1].
Sources (9)
  1. 1Where will 2026 rank among the hottest years on record? P... | Polymarketpolymarket.com
  2. 2Data.GISS: GISS Surface Temperature Analysis (GISTEMP v4)data.giss.nasa.gov
  3. 3Data.GISS: GISS Surface Temperature Analysis (GISTEMP v4)data.giss.nasa.gov
  4. 4Met Office Hadley Centre observations datasetsmetoffice.gov.uk
  5. 5Global land-ocean surface temperature data: HadCRUT5 | Climate Data Guideclimatedataguide.ucar.edu
  6. 6Met Office Hadley Centre observations datasetshadleyserver.metoffice.gov.uk
  7. 7Dataset Record: HadCRUT.5.0.0.0: Ensemble near-surface temperature anomaly grids and time seriescatalogue.ceda.ac.uk
  8. 8https://www.metoffice.gov.uk/hadobs/hadcrut5/HadCRUT5_accepted.pdfmetoffice.gov.uk
  9. 9Global land-ocean surface temperature data: HadCRUT5 | Climate Data Guideclimatedataguide.ucar.edu

8. What specific model uncertainties lead agencies like the Met Office and WMO to forecast 2026 as likely 'second-warmest' rather than definitively the warmest?

Met Office 2026 Forecast Mean1.46°C above 1850–1900 baseline (Met Office [1])
Met Office 2026 Forecast Range1.34°C–1.58°C (Met Office [1])
WMO 2024 Confirmed TemperatureAbout 1.55°C (WMO [2])
Temperature range overlap makes 2026's warmest year status uncertain. Agencies like the Met Office and WMO forecast 2026 as likely the 'second-warmest' rather than definitively the warmest, primarily due to the overlap between 2026's projected temperature range and 2024's confirmed temperature, alongside the probabilistic nature of El Niño forecasts [1][2][3][4][5][6]. The Met Office projects 2026 to be 1.46°C above the 1850–1900 baseline, with a range of 1.34°C–1.58°C [1]. This range significantly overlaps with 2024's confirmed temperature of approximately 1.55°C, as reported by the WMO [2], preventing a definitive assertion that 2026 will surpass 2024 as the warmest year [1][2].
El Niño forecast uncertainty contributes to 2026's probabilistic temperature ranking. Further uncertainty stems from the evolving nature of the El Niño-Southern Oscillation (ENSO) [3][4]. The WMO's February 2026 ENSO assessment indicated ENSO-neutral conditions as most likely through March–May (around 60%), with a rising chance of El Niño by May–July (around 40%), specifically noting the "spring predictability barrier" that reduces certainty [3][4]. Although an April 2026 update from the WMO suggests models are strongly aligned for an El Niño onset in May–July, potentially as a strong event, this remains a likelihood forecast, meaning 2026's global-mean temperature ranking is probabilistic rather than guaranteed [4][5]. This inherent uncertainty allows for a meaningful probability that 2024 could remain the record-holder, even if 2026 is widely expected to be among the top warmest years [1][6].
Sources (6)
  1. 12026 outlook: likely another year above 1.4°C - Met Officemetoffice.gov.uk
  2. 2WMO confirms 2024 as warmest year on record at about 1.55°C above pre-industrial levelwmo.int
  3. 3El Niño/La Niña Update (February 2026)public.wmo.int
  4. 4WMO: Likelihood increases of El Niñowmo.int
  5. 5Global Seasonal Climate Update for May-June-July 2026wmo.int
  6. 62026 will be the hottest year on record, leading scientist predicts | New Scientistnewscientist.com

9. Beyond ENSO, what other major climate phenomena, such as a major volcanic eruption in 2026, could prevent 2026 from setting a new temperature record?

Implied Probability of No Major VEI>=6 Eruption in 202688.5% [1]
Mount Ruang Eruption AltitudeApproximately 25 km [2]
Indian Ocean Dipole Forecast (June/July 2026)Exceeding +0.5°C [3]
Major climate phenomena beyond ENSO could prevent a temperature record. Beyond the influence of ENSO, significant climate events such as large explosive volcanic eruptions and shifts in other ocean-atmosphere variability, including the Indian Ocean Dipole (IOD), hold the potential to directly suppress global temperatures or alter established temperature rankings [4].
Large volcanic eruptions can significantly cool global temperatures. These eruptions contribute to surface cooling by injecting sulfur dioxide (SO2) into the stratosphere, where it forms sulfate aerosols that reflect solar radiation, potentially leading to a multi-year "volcanic winter" [4]. While a major eruption classified as Volcanic Explosivity Index (VEI) >=6 in 2026 is considered a low-probability event, with a market reporting an 88.5% implied probability of no such eruption, it remains a possibility [1]. For instance, the 2024 Mount Ruang eruption launched material approximately 25 km high and doubled stratospheric aerosol levels, with these sulfate particles expected to spread globally [2].
Ocean-atmosphere variability, like IOD, impacts global temperatures. Even with ENSO as the primary driver, co-occurring ocean-atmosphere variability can significantly influence temperature rankings [3]. The World Meteorological Organization's (WMO) May–July 2026 update forecasts a shift in the Indian Ocean Dipole (IOD) towards positive values, potentially exceeding +0.5°C by June/July 2026, which coincides with rapid El Niño intensification [3]. Earlier WMO reports for March–May 2026 also noted ENSO-neutral transition dynamics alongside a negative-to-weaken transition for IOD, underscoring the potential for non-ENSO ocean modes to persist alongside ENSO changes throughout 2026 [5].
Sources (5)
  1. 1Major volcano eruption (VEI ≥6) in 2026? Predictions & Od... | Polymarketpolymarket.com
  2. 2EarthCARE reveals global impact of Mount Ruang eruption - Earth Onlineearth.esa.int
  3. 3Global Seasonal Climate Update for May-June-July 2026wmo.int
  4. 4Volcanic winteren.wikipedia.org
  5. 5Global Seasonal Climate Update for March-April-May 2026public.wmo.int

10. What Could Change the Odds

Key Catalysts

Forecasts for 2026's global temperature ranking vary. Hansen claims 2026 will be the warmest year in the instrumental record, estimating a margin wide enough to break the 2024 record, though this depends on many remaining months being substantially warmer [1]. Carbon Brief forecasts 2026 as the second-warmest year on record, with a 19% chance to surpass 2024 as the warmest year, and says a strong El Niño later in 2026 would raise the chance that 2027 is hottest instead [2]. The Met Office’s 2026 outlook indicates a central global average temperature of 1.46°C above pre-industrial levels, with a forecast range of 1.34°C–1.58°C; the Met Office says 2026 is likely to be one of the four warmest years and that 2024’s 1.55°C remains the current warmest-year reference [3].
A key factor is the anticipated shift toward El Niño conditions, with WMO guidance for mid-2026 indicating this change, and the “Global Seasonal Climate Update” for Apr–Jun 2026 noting that increased probability in the equatorial Pacific east of the Date Line reflects likely transition into a warm ENSO state [4][5][6]. While Copernicus ERA5 bulletins show the year is already extremely warm in early 2026 (e.g., January 2026: 1.47°C above 1850–1900; March 2026: 1.48°C above 1850–1900), the outcome of the remaining months is what determines whether 2026 beats 2024 in annual ranking [7][8][1]. Polymarket’s “Where will 2026 rank among the hottest years on record?” lists the leading outcome as “2” (2nd hottest) at about 42% implied probability, with the next closest outcome as “1” at about 24%—suggesting the crowd more often expects 2026 to miss the #1 spot than to win it outright [9]. A related Polymarket market (“Will any month of 2026 be the hottest on record?”) shows very high current odds for ‘Yes’ (around mid-70% implied probability), consistent with expectations of strong second-half warmth but not the same as winning ‘hottest year’ overall [10][11].

Key Dates & Catalysts

  • Expiration: April 01, 2027
  • Closes: January 01, 2027
Sources (11)
  1. 12026 On Track for Warmest Year - by James Hansenjimehansen.substack.com
  2. 2State of the climate: Strong El Niño puts 2026 on track for second-warmest yearcarbonbrief.org
  3. 32026 outlook: likely another year above 1.4°C - Met Officemetoffice.gov.uk
  4. 4Global Seasonal Climate Update for April-May-June 2026wmo.int
  5. 5Global Seasonal Climate Update for May-June-July 2026wmo.int
  6. 6WMO Forecasts Strong El Niño From Mid-2026, Warns of Rising Global Temperatures and Rainfall Shiftsgulfnews.com
  7. 7Copernicus: Fifth-warmest January sees 2026 start with weather extremes across both hemispheres | Copernicusclimate.copernicus.eu
  8. 8Surface air temperature for March 2026 | Copernicusclimate.copernicus.eu
  9. 9Where will 2026 rank among the hottest years on record? P... | Polymarketpolymarket.com
  10. 10Will any month of 2026 be the hottest on record? Predicti... | Polymarketpolymarket.com
  11. 11Will any month of 2026 be the hottest on record? Predicti... | Polymarketbase.polymarket.com