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When is the Coldest Time of the Year? NOAA Map Shows the Details
Published: December 5, 2017
We've now entered the three-month stretch from December through February that typically features the coldest temperatures of the year in many locations across the United States.
Perhaps you are curious about the coldest time of the year where you live, historically speaking. These maps from NOAA's National Centers for Environmental Information (NCEI) provide the answer, showing the timeframe for when the coldest day of the year, on average, occurs across the U.S.
Residents in pockets of the Pacific Northwest, Southern California and southwestern Arizona get their coldest day of the year in mid-December.
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.
NOAA said the reason for this temporal discrepancy is due to the increased snow cover in the East, as well as in the Rockies. Increased snow cover reflects sunlight, keeping ground temperatures colder.
In Alaska, the coldest day of the year 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.
Despite its tropical locale, Hawaii does experience a coldest day of the year, relatively speaking. But through much of the island chain, the coldest day occurs in early February. The island of Lanai (west of Maui) experiences its coldest day during the first two weeks of January.
Keep in mind, these maps are not giving an actual forecast in any given year, 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 of the year, according to Dr. Brian Brettschneider, a climatologist with the University of Alaska-Fairbanks.
Lowest Average Temperature During the Year For Specific Cities
NCEI's 1981-2010 climate normals can also give us the city-specific average temperatures for every day of the year.
In the table below, you will find the coldest average-low temperature for a few cities in each region and the date(s) that this occurs, historically.
|Boston: 21.7° Jan. 17-20||Chicago: 16.1° Jan. 19-20||Billings, Montana: 16.7° Dec. 23-31||Atlanta: 34° Jan. 8-15|
|Burlington, Vermont: 9.5° Jan. 21||Detroit: 18.7° Jan. 19-23||Denver: 16.6° Dec. 15-20||Charlotte: 29.3° Jan. 11-15|
|New York: 26.6° Jan. 16-23||Fargo, North Dakota: -0.5° Jan. 17-22||Fairbanks, Alaska: -17.6° Jan. 17||Dallas: 36.9° Jan. 3-6|
|Philadelphia: 25.3° Jan. 15-23||Kansas City: 22.1° Jan. 14-21||Phoenix: 44° Dec. 21-24||Houston: 42.9° Jan. 5-13|
|Pittsburgh: 21.4° Jan. 18-22||Milwaukee: 15.2° Jan. 16-20||Portland: 34.5° Dec. 20-25||Nashville: 28.1° Jan. 15-20|
|Syracuse: 15.2° Jan. 17-25||Minneapolis: 7° Jan. 16-18||Salt Lake City: 21.5° Jan. 9-22||New Orleans: 44.4° Jan. 10-17|
|Washington D.C.: 28.3° Jan. 15-20||St. Louis: 23.4° Jan. 11-17||Seattle: 35.1° Dec. 18||Orlando: 48.8° Jan. 11-16|
Evolution of Average Highs and Lows During Winter
Finally, you can see how average high and low temperatures evolve for each month across the Lower 48 states from December through February.
Average low temperatures by month December-February.
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