The core of an arctic air mass moving toward South-central Canada today will move east-southeast and into New England with limited, if any moderation. The coldest point of the arctic air presence across the Northeast is around 5AM Saturday morning. At that time, Boston could plummet to -16F, Portland, ME -24F, and Burlington, VT -30F.

A much colder forecast as a vigorous upper trough across and to the east of the Black Sea region generates a chill that propels night temperatures into the 10-15F range at night in Ukraine and into Eastern Europe.

An exceptionally mild winter 2022-23 for New England but a brief period of arctic air visits later next week possibly for about 5 days. During that time Boston maximum temperatures could stay below freezing for up to 5 days including at least one night in the single digits.

The U.S. outlook to close January and through the first third of February is trending less cold. The primary reason is an increased westerly component aloft in the medium-range forecast easing the cross-polar flow of arctic air and increasing the milder Pacific influence on the U.S. thermal pattern. As a result, heating degree days forecasts are trending lower.