December 2025 signaled a decisive break from the recent decade of mild starts to winter. It registered as the first December since 2016 to feature both below-normal temperatures (-3.5°F departure) and above-normal snowfall (9.5 inches).

This wasn't just "cold"; it was volatile. The month was punctuated by repeated active Clipper systems dropping significant snow (Dec 6-7, Dec 13-14), arctic wind chills hitting -30F, and a rare severe weather outbreak on December 28.

Scientific consensus indicates the current "Pacific Zonal Flow" is a fragile anomaly. The atmospheric signals—specifically the "Great Lakes Hole" in the CPC temperature outlook—suggest a sharp rejection of the current mild pattern around January 15.

The Bottom Line: Winter Returns, But The "Intensity" Is The Variable.

While we have high confidence in the timing of the snapback (mid-month), the magnitude is still being resolved by the models. We are currently monitoring two critical variables that will define the second half of January:

The Depth of Cold: Will this be a standard return to seasonal norms, or will the Polar Vortex fragment enough to deliver sub-zero extremes?

The Moisture Connection: A return to cold is certain, but precipitation is not. We are watching to see if the storm track suppresses south (leaving us cold and dry) or phases correctly to deliver impactful snow.