It Was America's Warmest Winter On Record, NOAA Says

Winter was the warmest on record in the contiguous U.S. since the late 19th century, and was particularly warm from parts of the upper Midwest into the Northeast.

M​eteorologists group seasons into tidy three-month buckets that more closely follow average temperatures, rather than astronomical seasons that follow the changing sun angle. Meteorological winter follows the typically coldest months of the year from December through February.

E​xcept for some, it didn't feel all that cold this winter. Here are the highlights we noticed in the preliminary data.

A​ national winter record falls: December 2023 through February 2024 was the Lower 48's warmest winter in 129 years, according to data released Friday by NOAA's National Centers For Environmental Information.

That topped the previous record warm winter from 2015-16 by 0.82 degree Fahrenheit. In the realm of temperature data averaged over three months over the entire Lower 48 states, it's significant to top a previous record by a few tenths of a degree. So this winter's reading in the U.S. was an absolute pummeling of the old record.

W​armest winter for eight states: Iowa, Michigan, Minnesota, New Hampshire, New York, North Dakota, Vermont and Wisconsin each had their record warmest winter. Another five states - Illinois, Indiana, Maine, Missouri and Ohio - had their second warmest winter in 2023-24, according to NOAA.

Dozens of cities, too: At least 30 cities also tied or set their record-warmest winter, according to the Southeast Regional Climate Center (SERCC).

The majority of these were in the Midwest and Northeast, including Albany, New York; Des Moines, Iowa; and Milwaukee, Wisconsin. They also included typically frigid cities such as Caribou, Maine; Fargo, North Dakota; International Falls, Minnesota; and Sault Ste. Marie, Michigan.

A few western cities also had a record-warm winter, including Fresno, California, and Medford, Oregon.

Some clobbered previous records: This winter's mean temperature in F​argo, North Dakota, was over 4 degrees warmer than their previous record from 2011-12.

Looking at their temperature trace, only a period in mid-January and a couple of days near the end of February appeared to be colder than average.

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A​ccording to the SERCC, most of the record-warm winter cities from the Great Lakes to the Dakotas were 8 to 14 degrees warmer than average this winter.

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F​ebruary or May? Many of those same cities also had a record-warm February, punctuated by a late-month heat wave that shattered over 50 all-time record highs for any winter month.

I​t was also a record warm February in 130 years in four Midwest states - Iowa, Minnesota, Missouri and Wisconsin - according to NOAA.

L​east February snowpack in 20 years: Given all this warmth, it's no surprise that maintaining snow cover across the country was a challenge.

A​veraged over the entire month, February 2024 had the smallest snow cover over the contiguous U.S. in 20 years, according to data from NOAA.

F​or a few days over Presidents' Day weekend, snow cover ticked above average from a fresh blanket of Midwest and Ohio Valley snowfall.

B​ut as warmer air returned, most snow cover east of the Rockies melted away. By Feb. 26 – the first of the two warmest days of the record late-winter heat wave – less than 14% of the Lower 48 had snow on the ground. The snow cover map resembled one you might expect in late April or May, not late February.

Ice-free lakes: The warmth also left Great Lakes ice cover at a 51-year low for mid-February, including an ice-free Lake Erie and just a few small bays of Lake Superior with any ice.

Why so warm: One reason was the strong El Niño that had been in place; warmer winters are typical across the northern tier of states during a strong El Niño. However, Alaska-based climatologist Brian Brettschneider noted Thursday this El Niño winter was far and above much warmer than previous such winters since the mid-1970s.

T​here was also a lack of persistent blocking patterns – such as the Greenland block – that pull cold air from Canada and lock it into the U.S. for longer than a few days. Instead, blocking high pressure was common over central and eastern Canada, keeping the Midwest and Northeast persistently much warmer than usual.

The lack of snow and ice cover allowed more of the sun's energy to heat the ground and air above it, as opposed to melting snow or ice.

F​inally, winter has been the fastest-warming season in most of the U.S. since 1970, according to a study from Climate Central. They found that especially true in the Great Lakes and Northeast. That includes shorter cold snaps, less extreme cold and more unusually warm winter days now than before 1970.

M​ORE ON WEATHER.COM:

-​ Earth's Record-Warmest February Was 2024

-​ Does Warm Winter Mean Earlier Gardening And Yard Work?

-​ Climate Change Threatens Pond Hockey

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. His lifelong love of meteorology began with a close encounter with a tornado as a child in Wisconsin. He completed a Bachelor's degree in physics at the University of Wisconsin-Madison, then a Master's degree working with dual-polarization radar and lightning data at Colorado State University. Extreme and bizarre weather are his favorite topics. Reach out to him on X (formerly Twitter), Threads, Facebook and Bluesky.

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