The Climate Impact Company gas population weight HDD forecast for the 2025-26 heating season is updated and official. The new forecast is based on the just-issued U.S. month 1-6 climate forecast valid through next March. The adjusted outlook features 5 analogs for each month of the heating season helping to visually identify forecast confidence.

Utilizing the ECMWF windspeed probability forecasts for OCT-25 through JAN-26 across North America and Europe yield a tendency for above normal windspeed risk across northern latitudes and below normal windspeed across the Southern U.S. and Southern Europe.

The preliminary U.S. winter 2025-26 gas population weight heating degree day forecast is issued. The outlook indicates near the 30-year normal HDD for November, somewhat warmer than normal December, shifting colder than normal mid-to-late winter, and a mild March. Due to the presence of a strong marine heatwave (MHW) in the Northeast Pacific combined with a stronger than normal North Atlantic warm hole (NAWH) south of Greenland, the risk of an “Alaskan ridge bridge” and compensating downstream polar vortex over Central Canada increases for JAN/FEB 2026 if the sea surface temperature anomaly (SSTA) patterns present now persists through meteorological winter.

A short-lived La Nina is ahead and supported by vast cooling of the subsurface equatorial East Pacific during recent weeks. However, if the warming Northeast Pacific persists in early 2026, the La Nina episode ends, possibly abruptly and the warm waters of the Northeast Pacific spread south possibly causing an El Nino onset middle third of 2026 which could become intense later next year.