The Coldest Time Of The Year In Much Of US Is Typically Late January

January is known for frigid temperatures and for many the average coldest day of the year happens later in that month.

N​OAA map shows when the average coldest day of the year typically occurs in the United States: From the Northern Plains to the Midwest, Southeast and Northeast, the last two weeks of January are typically the coldest time of year. Only some parts of northern Michigan typically are coldest after Feb. 1.

From the Front Range of the Rockies westward, this coldest time of year is usually much earlier in December or early January.

The reason for this discrepancy from east to west is the frequent plunges of frigid arctic air chilled over Alaska and Canada into the Midwest and Northeast in January. West of the Rockies, these mid-winter Arctic plunges are less frequent. Instead, Pacific storms can usher less cold air into the West, even in the heart of winter.

In Alaska, the coldest time of year is also usually in January. In Hawaii, much of the island chain experiences the coldest day, relatively speaking, in February or early March.

The maps are derived from U.S. climate normals provided by the National Centers for Environment Information (NCEI): The dataset consists of the latest 30-year average of weather data, including daily high and low temperatures, for various cities throughout the U.S.

The map shows the average timeframe the coldest air of the season arrives. In any given year, the actual coldest day for your area may occur before or after the time shown on the map.

The coldest temperatures of the year usually occur when bitterly cold arctic air in Canada is pulled southward into the U.S. The arctic outbreaks usually happen around the average coldest time of the year, like we are seeing this month.

Recent years show the atmosphere can deliver the coldest air sooner or later than the average: A bitterly cold outbreak in early March 2019 was the coldest of the season in Great Falls, Montana (minus 32 degrees); Dallas (21 degrees); and Wichita, Kansas (2 degrees).

In winter 2022-2023, late December brought the coldest air to many places, including Chicago (minus 8 degrees); Nashville, Tennessee, (minus 1 degree); and Atlanta (8 degrees).

All-time record lows are spread across December, January or February for many cities: Boston, New York City's Central Park and Philadelphia all set their records in a Feb. 9, 1934, cold outbreak. Washington, D.C., set its record on Feb. 11, 1899.

Many Midwestern cities set their all-time records in January, including Chicago (Jan. 20, 1985), Cleveland (Jan. 19, 1994) and Minneapolis-St. Paul (Jan. 21, 1888).

In the South, the January 1985 cold outbreak set records that still stand in Charlotte and Raleigh, North Carolina; Charleston, South Carolina; and Nashville, Tennessee. However, the historic February 1899 cold outbreak, arguably the greatest in modern history, still is the all-time record holder in Atlanta; Dallas; Little Rock, Arkansas; and Tallahassee, Florida, among other cities.

Western all-time record cold varied from as early as Dec. 11, 1932, in downtown San Francisco to Feb. 15, 1936, in Great Falls, Montana. Anchorage (minus 34 degrees) and Fairbanks (minus 66 degrees) each set their all-time cold records in early to mid-January.

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.