When The First Below-Zero Temperatures Usually Arrive In US

Subzero temperatures are routinely seen in northern parts of the U.S. during winter, but the timing of arrival varies and some don't experience this level of bone-chilling cold each season.

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The Early Birds: Temperatures typically drop below zero earliest in the season near the Canadian border in the north-central U.S. and in the Rockies higher elevations.

For example, Grand Forks, North Dakota, and Great Falls, Montana, usually see their first temperature of minus 1 or colder by late November, according to the 30-year average from 1991 to 2020.

Decemberrr's Subzero Club: Early to mid-December is when the first subzero readings have typically happened in Denver; Billings, Montana; Minneapolis; and Caribou, Maine. Omaha, Nebraska, and Burlington, Vermont, wait a bit longer until late in the month, on average.

J​anuary, If At All: Cities around the southern Great Lakes and interior Northeast typically see their first below-zero temperatures, including Chicago; Detroit; Indianapolis; Albany, New York; Buffalo, New York; and Pittsburgh. While those cities saw subzero cold in a majority of the winters during the 30-year average period, it doesn't happen every season.

It's Rarer On The East Coast: New York City had only two winters with subzero cold in the 30-year period from 1991-2020, one in late January and another in mid-February.

In those winters when Boston does dip below zero one or more times, the average date of the first such reading is Jan. 18. But Beantown only experienced seven winters with any below-zero temperatures during the 30-year period from 1991 to 2020.

A​rctic High Pressure Is Key: For subzero cold to infiltrate areas where it doesn't happen every winter, arctic high pressure is almost always involved.

T​hese strong areas of high pressure push into the U.S. one or more times each winter, dragging in arctic air that has a source region anywhere from Russia's Siberia to Alaska or northern and western Canada.

T​he combination of the cold air plus light winds under clear skies near the center of high pressure (blue H below) allows heat to efficiently escape from near earth's surface at night. That allows temperatures to plunge, sometimes sending thermometers below zero.

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Chris Dolce has been a senior meteorologist with weather.com for over 10 years after beginning his career with The Weather Channel in the early 2000s.