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Traditional Coldest Day of The Year: It Depends On Location

January 23, 2023
By WeatherBug Sr. Meteorologist, Chad Merrill
Winter---a season that many people automatically describe as the coldest time of the year with snow and gusty winds. Even the Deep South has its share of chilly days with occasional frost and even snow during those anomalous winter storms. While it’s traditionally the coldest season of the year, did you know that not every part of the U.S. shivers at the same time?

The current climate averages are derived from weather data using daily observations from 1991 to 2020. From that dataset, meteorologists calculate average low and high temperatures for each month of the year and each day of the week. Meteorologists then hone in on the one day or week of the year that on average is the coldest of the year.

The typical weather patterns associated with each region of the U.S. help to dictate when the coldest day or week of the year occurs. For much of the western High Plains and lower elevations of the West, including the Desert Southwest, the coldest part of winter occurs in December to early January. The reason it occurs early during the winter here is because the shortest daylight of the year and lowest sun angle of the year occurs in the first half of winter. 

Recall the winter solstice always occurs around December 20 and this marks the day with the shortest amount of daylight in the Northern Hemisphere. The longer stretch of nighttime hours around this time of the year helps to radiate away the maximum amount of the sun’s radiation from the previous day. Not to be outdone, clouds and precipitation limit warmth during the daytime. 

Phoenix, for instance, typically sees its coldest minimum temperatures between December 15 and January 1 when the average morning low is 44 degrees. December and January are also the fifth and sixth wettest months of the year. So, a combination of shorter daylength, clouds and rain often keep temperatures the coldest from mid-December to early January.

For the Mountain West, including the Rockies, Wasatch and Sierra, these high elevation spots see the most snow of any other part of the U.S. Snowpack starts to increase in the fall and usually snow covers the ground through at least early Spring. The longer the snow is on the ground, the colder the days will get deeper into the winter, even after daylight begins to increase once the Winter Solstice has occurred in late December.  

Therefore, instead of the coldest days of the year occurring in December, the mercury reaches its lowest point in January or February. Moab, Utah, at an elevation of 4,000 feet, has its coldest temperatures of the year between January 4 and 11. Similarly, Grand Junction, Colo., at an elevation of 4,858 feet, sees its coldest temperatures on average between January 5 and 7. 

Much of the southern Tier from Texas to Florida and Carolinas has its coldest stretch between the end of December and first 20 to 25 days of January. This marks the time of the year cold fronts are most likely to sweep all the way to the Gulf Coast and bring the biggest chill of the season. The southern Plains to Southeast often see occasional cold fronts that contribute to a later date for their coldest weather of the year.  

The remainder of the U.S. from the eastern Plains to the Tennessee and Ohio valleys, Great Lakes, Midwest, Mid-Atlantic and Northeast share the same coldest days of the year in a typical winter. Their coldest stretch of the year is from mid-January to mid-February. This time period coincides with the highest frequency of cold fronts, snow accumulation and low sun angle. 

The Great Lakes typically see at least marginal ice accumulation after a long period of cold weather. This doesn’t happen until the second half of winter. The cold or ice-covered Great Lakes act as Mother Nature’s air conditioner. For instance, Detroit does not see its coldest days occur until mid-January to early February. 

Not to be outdone, snowpack remains on the ground for weeks on end across interior New England in a normal winter. The long stretch of days with snowpack does more to temperatures in this region than increasing daylight after the Winter Solstice occurs in late December. Therefore, the coldest days of the year occur in winter’s second half. For Berlin, N.H., this happens between January 7 and February 3.

The bottom line is when the coldest day of the year occurs is all relative and depends on where you live. Though each year is different and may not always conform to the usual trends, this information could be useful as a guide before planning your winter vacation.