- Will global temperature increase by less than 1.30ºC in October 2026?3¢3%
- Will global temperature increase by between 1.30ºC and 1.34ºC in October 2026?8¢8%
- Will global temperature increase by between 1.35ºC and 1.39ºC in October 2026?13¢13%
- Will global temperature increase by between 1.40ºC and 1.44ºC in October 2026?16¢16%
- Will global temperature increase by between 1.45ºC and 1.49ºC in October 2026?18¢18%
- Will global temperature increase by more than 1.49ºC in October 2026?75¢75%
A strengthening El Niño, with Niño 3.4 sea surface temperature anomalies already exceeding +3°C in mid-October 2026 and forecast to intensify further through year-end, serves as the dominant driver pushing October global mean surface temperature anomalies toward the upper end of recent ranges. Copernicus ERA5 data show September 2026 at 1.63°C above the 1850–1900 baseline—the second-warmest September on record—while early October observations and ensemble projections indicate the month is tracking near or above 1.6°C, supported by record extra-polar ocean warmth and the lagged warming effect of the event. Market-implied odds clustered tightly between 1.35–1.49°C reflect remaining uncertainty from intra-month variability, model spread in the final weeks, and precise measurement methodologies across datasets like ERA5, with new daily analyses and updated seasonal forecasts expected to refine the outcome before month-end resolution.
Rules
This market will resolve according to the value reported by the Global Land-Ocean Temperature Index for October 2026 when it is released. An anomaly within a named bracket for October 2026 is necessary and sufficient to resolve this market immediately once the data becomes available, regardless of whether the figure for October 2026 is later revised. The brackets are mutually exclusive and collectively exhaustive: each range is inclusive of both of its stated endpoints, and the reported anomaly (to the nearest 0.01ºC) falls within exactly one bracket. The primary resolution source for this market will be the figure found in the table titled "GLOBAL Land-Ocean Temperature Index in 0.01 degrees Celsius" under the column "Oct" in the row "2026" (https://data.giss.nasa.gov/gistemp/tabledata_v4/GLB.Ts+dSST.txt). If NASA's "Global Temperature Index" is rendered permanently unavailable, other information from NASA may be used. If no information for October 2026 is provided by NASA by December 1, 2026, 11:59 PM ET, this market will resolve to the lowest range bracket.