Tuesday, December 8, 2020

With Official Start to Winter Two Weeks Away, Here's When the Coldest Time of Year Occurs

Chris Dolce

Published: December 7, 2020
Article imageThe timeframe you would expect the coldest low temperatures of the year to occur, based on 1981-2010 temperature averages.

As we near the winter solstice, the coldest time of year in much of the U.S. outside of the West is still about a month away.

Maps from NOAA's National Centers for Environmental Information (NCEI) show when the coldest day of the year, on average, occurs across the United States.

The eastern half of the country, as well as the higher elevations of the Rocky Mountains, typically see the coldest day in mid- to late January.

Pockets of the Pacific Northwest, Southern California and southwestern Arizona get their coldest day in mid-December.

The reason for this discrepancy is due to the increased snow cover in the East, as well as in the Rockies. Increased snow cover reflects sunlight and keeps ground temperatures colder.

Article imageDays of Alaska's coldest low temperatures during an average year, using 1981-2010 averages.

In Alaska, the coldest day usually occurs in mid- to late January for much of the state, with the exception of locations north of the Arctic Circle, where the coldest day tends to occur in February or during the first half of March.

In Hawaii, much of the island chain experiences the coldest day, relatively speaking, in early February. The island of Lanai, west of Maui, experiences its coldest day during the first two weeks of January.

These maps are not giving an actual forecast, but rather an average date for the coldest day of the year. This average is derived from NCEI's 1981-2010 U.S. climate normals, a dataset that consists of NCEI's 30-year average of certain climatological variables, including average daily high and low temperatures for various cities throughout the U.S.

Because the map is showing an average and not a forecast, the actual coldest day of the year for your area may occur before or after the timeframe illustrated in the graphic.

In fact, for most places in North America, the day of the year when the coldest temperature occurs is typically a week or more later than the coldest average-low temperature, according to Dr. Brian Brettschneider, a climatologist with the University of Alaska-Fairbanks.

Coldest Average Low Temperature for Specific Cities

NCEI's 1981-2010 climate normals also provide the city-specific average temperatures for every day of the year.

The tables below list the coldest average-low temperature for a few cities in each region and the date(s) this occurs, historically.

Article imageThe coldest average low temperatures of the year and when they occur, based on 1981-2010 averages.
Article imageThe coldest average low temperatures of the year and when they occur, based on 1981-2010 averages.
Article imageThe coldest average low temperatures of the year and when they occur, based on 1981-2010 averages.
Article imageThe coldest average low temperatures of the year and when they occur, based on 1981-2010 averages.

You can see how the average high and low temperatures evolve across the Lower 48 states from December through February.

Article imageAverage high temperatures by month December through February.
Article imageAverage low temperatures by month December through February.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.




 

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