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Will NASA GISS report a global surface temperature anomaly of at least +1.40 °C (vs. 1951–1980) for November 2026?

deadline 2026-12-20 confidence medium tier 1 evidence
49%Asturna estimate

Resolution criterion

Resolves YES if the NASA GISS file GISTEMP v4 land-ocean monthly means (https://data.giss.nasa.gov/gistemp/tabledata_v4/GLB.Ts+dSST.csv), read for the first time on or after 2026-12-20, shows a value >= +1.40 °C for November 2026 (row 2026, column Nov). The value read at that moment is final; later revisions do not change the outcome. If the value is not yet published on 2026-12-20, the check is repeated until 2026-12-30, after which the question is voided. Also voided if NASA changes the dataset version or the 1951–1980 baseline. Reference at creation: +1.38 °C (September 2026). Data: GISTEMP Team, GISS Surface Temperature Analysis (GISTEMP), version 4, NASA Goddard Institute for Space Studies.

Verified starting state

Computed base rate: 46% of two-month changes in the NASA GISTEMP monthly anomaly since 1990 reached the change implied by this threshold (threshold 1.4 °C rounded up to 0.05 °C; reference 1.38 °C in 2026-09). Overlapping windows: small effective sample.

What pushes it up

What pushes it down

What would move this number most

Late-autumn atmospheric circulation patterns and ocean surface temperature trends throughout November 2026.

How this number is built

Deadline2026-12-20
Base rate46%
Best evidencetier 1 · 1 article(s) used
Independent runs48 · 49 (spread 1 pts)
Confidencemedium
Evidence capnot triggered
Last revised2026-10-18 09:08
Modelgemini-3.7-flash

Sources consulted

NASA GISS (GISTEMP v4) - official data series that settles this questiontier 1 · NASA GISS (GISTEMP v4) · 2026-10-18

Probability history

2026-10-18 09:08 49% 3 article(s) on file · gemini-3.7-flash
  • What pushes it up. September 2026 GISTEMP anomaly reached +1.38 °C, requiring only a modest +0.02 °C rise to meet the threshold [tier 1].
  • What pushes it up. Early Copernicus ERA5 data for the first 16 days of October 2026 shows a warm anomaly of +0.83 °C vs 1991–2020, pointing to sustained global warmth into late autumn [tier 1].
  • What pushes it down. Month-to-month volatility in global temperature anomalies routinely exceeds 0.05 °C, making negative fluctuations common [tier 1].
  • What pushes it down. Historical two-month anomaly changes from this baseline yield an empirical base rate below 50% (46%) [tier 1].
  • What would move this number most. Late-autumn atmospheric circulation patterns and ocean surface temperature trends throughout November 2026.
2026-10-18 09:07 40% 3 article(s) on file · gemini-3.7-flash
  • What pushes it up. August 2026 established a high baseline of +1.40 °C, requiring only a modest +0.05 °C two-month rise to reach the resolution threshold [tier 1].
  • What pushes it up. Copernicus ERA5 reanalysis for the first 16 days of October 2026 shows a warm global anomaly of +0.83 °C against the 1991–2020 baseline [tier 1].
  • What pushes it down. Historically, only 38% of two-month increments achieve a +0.05 °C gain, reflecting frequent short-term monthly volatility [tier 1].
  • What pushes it down. The 16-day ERA5 metric is an incomplete, partial-month signal and differs in methodology and baseline from the final GISTEMP v4 land-ocean calculation [tier 1].
  • What would move this number most. The evolution of global temperatures during the second half of October 2026 and the exact land-ocean blending in the final NASA GISTEMP v4 calculation.
2026-10-17 09:10 50% 3 article(s) on file · gemini-3.7-flash
  • What pushes it up. September 2026 was already high at +1.38 °C, requiring an increase of only +0.02 °C to reach the +1.40 °C threshold [tier 1].
  • What pushes it up. Preliminary ERA5 reanalysis data for the first 15 days of October 2026 shows a strong anomaly of +0.83 °C relative to 1991–2020, indicating continued high global anomalies entering late 2026 [tier 1].
  • What pushes it down. Two-month temperature fluctuations frequently swing downward by several hundredths of a degree Celsius due to standard monthly climate variability [tier 1].
  • What pushes it down. Partial ERA5 data covers only half of October and represents a weak leading indicator that does not ensure elevated temperatures will persist through November [tier 1].
  • What would move this number most. The magnitude of month-to-month global climate variability and sea-surface temperature changes between September and November 2026.
2026-10-17 09:08 41% 3 article(s) on file · gemini-3.8-flash
  • What pushes it up. August 2026 recorded a high baseline of +1.40 °C, requiring an increase of only +0.05 °C to meet the +1.45 °C threshold [tier 1].
  • What pushes it up. Early Copernicus ERA5 data for the first 15 days of October 2026 shows an anomaly of +0.83 °C vs. 1991–2020, which roughly converts to near the +1.45 °C mark against 1951–1980 [tier 1].
  • What pushes it down. Historically, two-month positive shifts of +0.05 °C or more occur only 38% of the time, establishing a sub-50% prior [tier 1].
  • What pushes it down. The 15-day ERA5 indicator is a partial month observation subject to weather-driven fluctuations in the second half of October, and ERA5 differs methodologically from NASA GISTEMP [tier 1].
  • What pushes it down. Available press updates offer no specific preliminary numbers for the full GISTEMP October anomaly [tier 1, tier 4].
  • What would move this number most. Whether global land and sea surface temperature anomalies in the second half of October 2026 stay elevated enough to keep the full-month GISTEMP average at or above +1.45 °C.
2026-10-16 20:08 55% 3 article(s) on file · gemini-3-flash-preview
  • What pushes it up. The required increase from the September 2026 reference of +1.38 °C to the +1.40 °C threshold is only +0.02 °C [3].
  • What pushes it up. Early ERA5 data for the first half of October 2026 shows a high anomaly (+0.82 °C vs 1991–2020), which typically translates to a GISTEMP anomaly above 1.40 °C when adjusted to the 1951–1980 baseline [1].
  • What pushes it down. Monthly global temperature anomalies are subject to significant short-term volatility, which can easily offset the current warming trend [3].
  • What pushes it down. The historical base rate for this specific two-month change is slightly below 50%, suggesting that a minor decline or stagnation is statistically common [3].
  • What would move this number most. The degree of temperature persistence between October and November 2026 and the potential for short-term cooling fluctuations.
2026-10-15 20:01 35% 3 article(s) on file · gemini-3.7-flash
  • What pushes it up. Baseline temperatures remain near record warmth, with August 2026 at +1.40 °C requiring only a modest +0.05 °C increase to hit the threshold [tier 1].
  • What pushes it up. Early Copernicus ERA5 data for the first 13 days of October 2026 indicates a high anomaly of +0.82 °C above 1991–2020, confirming sustained warmth [tier 1].
  • What pushes it down. The historical two-month transition base rate to gain +0.05 °C from August to October is modest at 38% [tier 1].
  • What pushes it down. An ERA5 anomaly of +0.82 °C against 1991–2020 roughly equates to approximately +1.40 °C to +1.43 °C against the 1951–1980 baseline, tracking slightly below the required +1.45 °C [tier 1].
  • What would move this number most. Whether global temperature anomalies in the second half of October accelerate enough to lift the monthly average over +1.45 °C in the GISTEMP v4 processing.
2026-10-14 09:07 49% 3 article(s) on file · gemini-flash-latest
  • What pushes it up. The required increase from September 2026 (+1.38 °C) to reach the +1.40 °C threshold is only +0.02 °C, well within typical positive monthly variance [tier 1].
  • What pushes it up. Early Copernicus ERA5 data for the first 12 days of October 2026 shows an anomaly of +0.81 °C vs. 1991–2020, indicating continued high global warmth roughly consistent with ~1.4 °C on the 1951–1980 baseline [tier 1].
  • What pushes it down. Base rate analysis indicates two-month changes reach the required threshold only 46% of the time, reflecting natural month-to-month volatility [tier 1].
  • What pushes it down. Monthly global temperature anomalies frequently drop by 0.05 °C to 0.15 °C between early autumn and late autumn depending on ENSO phase and oceanic variability [tier 1].
  • What would move this number most. The trajectory of global sea surface temperatures and ENSO conditions between October and November 2026, which drive short-term swings in global anomalies.
2026-10-14 09:07 39% 3 article(s) on file · gemini-flash-latest
  • What pushes it up. August 2026 anomaly was already high at +1.40 °C, meaning only a modest +0.05 °C increase is needed to meet the threshold [tier 1]
  • What pushes it up. Copernicus ERA5 early data for the first 12 days of October 2026 shows a +0.81 °C anomaly relative to 1991–2020, which roughly translates to ~1.44–1.48 °C relative to the 1951–1980 GISTEMP baseline [tier 1]
  • What pushes it down. The two-month historical base rate for an anomaly increase of this magnitude is 38%, reflecting seasonal and natural month-to-month variability [tier 1]
  • What pushes it down. Twelve days of ERA5 data cover less than half the month and represent an early, volatile indicator that may not reflect full-month land-ocean GISTEMP v4 averages [tier 1]
  • What would move this number most. Global weather patterns and sea surface temperatures over the second half of October 2026, which could easily shift the final monthly average above or below 1.45 °C.
2026-10-13 09:17 58% 2 article(s) on file · gemini-3-flash-preview
  • What pushes it up. The required increase from the September 2026 anomaly of +1.38 °C to the +1.40 °C threshold is a very small margin of 0.02 °C [1].
  • What pushes it up. Early ERA5 indicator data for October 2026 (+0.81 °C vs 1991-2020) suggests a high global anomaly that, when adjusted to the GISTEMP baseline, likely exceeds 1.40 °C [1].
  • What pushes it down. Monthly global temperature anomalies are subject to significant short-term volatility from weather patterns and natural variability [1].
  • What pushes it down. The historical base rate for this specific two-month delta is slightly below 50%, indicating that such an increase is not guaranteed despite the warming trend [1].
  • What would move this number most. Short-term atmospheric variability and the specific state of the El Niño-Southern Oscillation (ENSO) in late 2026.
2026-10-13 09:07 39% 2 article(s) on file · gemini-flash-latest
  • What pushes it up. August 2026 set a high baseline at +1.40 °C, requiring only a +0.05 °C upward shift to resolve YES [tier 1].
  • What pushes it up. Copernicus ERA5 early October data (first 11 days) indicates an anomaly of +0.81 °C vs. 1991–2020, which translates roughly to the threshold range vs. 1951–1980 [tier 1].
  • What pushes it down. Historically, only 38% of two-month steps achieve the necessary +0.05 °C rise, making a drop or sub-threshold reading the base-case outcome [tier 1].
  • What pushes it down. The ERA5 indicator covers only 11 days of October and represents an incomplete partial-month sample subject to late-month variability [tier 1].
  • What would move this number most. Late-month Northern Hemisphere atmospheric circulation and weather systems across the remainder of October 2026.