Warm surge to bring midsummerlike heat, humidity across East and Midwest

A burst of midsummerlike heat is set to sweep into the Midwest and East after a cool start to May, with temperatures climbing into the 80s and near 90 degrees in some cities. AccuWeather says the warmest weather of the year so far is likely to arrive early next week, and the National Weather Service says heat is already spreading across the eastern U.S.

Much of the Midwest and interior Northeast has run 5 to 10 degrees below the historical average so far this month, setting up a sharp swing that will catch people and systems before they have fully adjusted. AccuWeather says 90-degree heat is possible as far north as the Philadelphia area by Tuesday, while dew points in the 60s will make the humidity stand out across the Northeast. In some spots, RealFeel temperatures could approach or top 100 for a few hours on two or three days, a level that turns a moderate-looking forecast into a much bigger strain on the body.

That matters because the first real heat event of the season often hits before school buildings, athletic programs, utilities and outdoor crews have acclimated. Air-conditioning demand can jump quickly when a cool spring gives way to sudden humidity, and the combination of heat and moisture raises the risk of heat illness for workers, students and anyone spending long stretches outside. AccuWeather says some places in the East may see their highest temperatures of the year so far early next week, and the warm spell may be brief in the Upper Midwest and some coastal Northeast locations, but even a short stretch can be disruptive when the season has not yet settled.

The same broad pattern is producing sharp contrasts across the country. The National Weather Service says severe storms, very large hail, strong tornadoes and damaging winds are expected from the Great Lakes into the central and southern Plains even as the eastern U.S. warms. That kind of split is typical in May, a volatile month that Weather.com says averages 278 U.S. tornadoes, more than any other month. The same source says 37 storms formed in the Atlantic Basin before June 1 from 1851 to 2025, with Ana in 2021 the most recent May storm.

The spring has already shown how quickly the weather can flip. Philadelphia reached 91 degrees, Washington, D.C. reached 91, New York City hit 90 and Baltimore climbed to 93 on April 15, 2026, before a later cold snap brought freeze risk back to parts of the Midwest and Northeast. AccuWeather notes that April 16, 2002 was the last earlier 90-degree reading in Philadelphia before that warmup, underscoring how unusual the early-season swings can be when heat surges before summer is fully underway.