During November, La Nina is weak but established with both oceanic and atmospheric characteristics. The Nino34 SSTA cools to -0.8C, the strongest (cool) signature of this episode. The southern oscillation index shifted to (mostly) strong positive phase during November, indicating a La Nina atmosphere has formed. The subsurface cool fuel to maintain La Nina is weak-to-moderate and slightly less cool during the past 1-2 weeks.

Latest review of what to expect for U.S. gas population weight HDD forecasts for the 2025-26 cold season. November was warm with colder weather arriving for December followed by a January thaw and seasonably cold late winter. The climate forecast is SSTA-based and doubts major polar vortex events except for early and late meteorological winter but with limited exposure to the high population East.

Operational forecasts continue to indicate a wet weather shift to Brazil. The mega-cluster ensemble indicates wet weather risk is highest in Northeast Brazil into the weekend while Argentina turns drier. The drier trend for Argentina is also evident during the medium range while wet focus shifts to East Brazil.

The projected SSTA regime and SSW risk are found in 7 different analog years in the modern climate era (since the mid-to-late 1990’s). Each year has an assigned statistical weight based on the strength of the analog. The consensus of the analog years yields an above normal snowfall each month of meteorological winter 2025-26 in Chicago and Boston (except for February).