Regional Stratospheric Warming Episode Eastern North America Late January

Climate Impact Company Midday Update

Issued: Thursday January 15, 2026

Highlight: Stratospheric warming takes place across eastern North America later 11-15-day period. This scenario is potential significant cold air producer.

Fig. 1: The 12Z GFS Day-15 10 MB temperature anomaly forecast indicates a significant regional stratospheric warming event.

Discussion: At midday, the 12Z GFS indicates evolution of a significant REGIONAL STRATOSPHERIC WARMING EVENT across eastern North America occurring mid-to-late 11-15-day period (Fig. 1). The warming is likely in response to a moderate to strong eastward shifting convection phase of the Madden Julian oscillation (MJO) across the equatorial Pacific. The episode supports potential for significant cold. The 12Z GFS develops cold across Canada in the 6-10-day period (Fig. 2) and drops the cold into the East, a colder change, in the 11-15-day period (Fig. 3).

Fig. 2-3: The 12Z GFS medium range temperature anomaly forecast.

Table 1: The midday 12Z GFS U.S. gas population weight HDD projections into later January.