Boston experienced its second-coldest December in 25 years in 2025, with average temperatures plunging below freezing as a blast of Arctic air cast a bitter chill over the region.
The average high temperature for the Massachusetts city last month was 31.3 degrees, which was just slightly warmer than in 2017, when December highs reached a 25-year low of 30.7 degrees. Throughout much of December, a weakening of the polar vortex saw Arctic air sweeping in.
At the same time, a southward dip in the jet stream channeled that frigid air across the central and eastern United States. Millions have had to grapple with higher bills over the festive season as the lower temperature left homes and businesses requiring more energy to stay warm…