Will the 2026–27 El Niño be the strongest on record?: live odds and probabilities

Market rules and resolution

This market will resolve to "Yes" if the peak RONI for the 2026–27 El Niño is above 2.40°C, the highest Relative Oceanic Niño Index (RONI) value on record. Otherwise, this market will resolve to "No". The peak RONI is the single highest RONI value reported by NOAA's Climate Prediction Center (CPC) across the overlapping three-month seasons ASO 2026, SON 2026, OND 2026, NDJ 2026-27, and DJF 2026-27, as reported in official NOAA CPC RONI updates. The record to beat is +2.40°C, set in DJF 1982-83, the highest RONI value for any three-month season in CPC's record. A peak RONI of exactly 2.40°C ties the record and resolves this market to "No". The first published RONI value for each listed season is final and governs this market's resolution. This market may resolve immediately upon NOAA's first publication of a RONI value of above 2.40°C for any listed season. If CPC's RONI dataset becomes temporarily unavailable, this market may be extended for up to 7 days. If CPC's RONI dataset is permanently discontinued, a consensus of credible reporting may be used. If the dataset remains unavailable after 7 days and there is no consensus of credible reporting, this market resolves to "No". No subsequent revision to a season's value will be considered or will change the outcome once that season's first value has been published. The +2.40°C threshold is fixed for the purposes of this market; any later revision to a historical season's RONI value will not change it. The resolution source for this market is the official NOAA CPC RONI updates, available here: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/