Some 400 sites on Wednesday posted record high temperatures for a March 14, according to the National Climatic Data Center -- and most of those were right smack in the Midwest.
Dozens of cities were in the 80s, and the warmth pattern is hardly over: a large swath, from Georgia and Florida to Montana, can expect to see records fall on Thursday, weather.com reported.
On Wednesday, the hottest spots were in Illinois, Indiana, Iowa, Kansas and Missouri.
Greensburg, Kan., saw the highest temp -- 88 degrees Fahrenheit, 6 degrees warmer than its previous record for a March 14 set in 1935.
High temperature records have been shattered this week from Florida to the U.S.-Canada border, with the variance from normal highs most pronounced in the Northern Plains, where recent temperatures in the 60s were as much as 30 degrees above normal.
The warm spell is expected to last into early next week.
The unusually warm air east of the Rocky Mountains was courtesy of a high-pressure system trapping cold air farther north, meteorologists said.
"We have a lot of warm, moist air from the Southwest pulling into our area, causing this pleasant weather," Chicago-area National Weather Service meteorologist Amy Seeley said.
Reuters contributed to this report.
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