Nearly 100 Million Face Severe Thunderstorm Risk on Wednesday While Heat Strikes the South and East
Strong to severe thunderstorms could strike nearly half the states in the U.S. on Wednesday as colder air from the north and west slams into unseasonably warm and moist air surging north from the south.
Brace yourself for a wild Wednesday if you live in one of at least 25 states that have the potential for severe thunderstorms today through early Thursday morning. The Storm Prediction Center (SPC) has outlined portions of several states for a marginal, slight, to enhanced risk, levels one, two, and three out of five, for severe thunderstorms.
6/18 2:26 AM CDT: Scattered severe storms are expected later today from parts the southern Plains to the southern Great Lakes. Scattered severe/damaging winds, isolated large hail, and a few tornadoes all appear possible. pic.twitter.com/i04tkWUBMv
— NWS Storm Prediction Center (@NWSSPC) June 18, 2025
The Great Lakes, Midwest, Missouri Valley, and southern plains regions have the highest probability of experiencing severe thunderstorms as a strong cold front collides with warm, moist air surging north out of the Gulf. The total area of the country at risk includes nearly 100 million people.
Flooding is Another Risk for Several Million People
A corridor that features the highest risk category, an enhanced risk, stretches from southern lower Michigan through parts of Ohio, Indiana, Illinois, and Missouri. This is where the potential for tornadoes will be highest. Damaging winds and large hail are the major threats for most of the regions at risk.
The area outlined for potential flooding in the central U.S. on Wednesday overlaps the main regions highlighted by the SPC for severe thunderstorm potential. The Weather Prediction Center (WPC) has outlined a large portion of the country for a marginal to slight risk, levels one and two out of five, respectively, for excessive rainfall that could produce flash flooding.
The areas targeted for flooding include most of the Midwest and Ohio Valley region, as well as a smaller portion of the Mid-Atlantic and Northeast regions. Northern Illinois, including Chicago, southern lower Michigan, and a swath of the Tennessee Valley, has the highest probability for heavy rainfall. Over 100 million people will be at risk, according to the WPC.
Hotspots and Elevated Fire Weather Conditions
The western U.S. and most of the East Coast will be warmer than usual on Wednesday. High temperatures should top out between 5 and 15 degrees above average. In the West, that means highs in the 80s all the way north to the Canadian border in Washington, Idaho, and Montana.
Hot and humid conditions are expected over the next couple of days across ENC. This will lead to a notable heat risk for those without adequate cooling, and those planning to spend time outdoors. Stay cool and hydrated! #ncwx pic.twitter.com/hh1fkc6Uvl
— NWS Newport/Morehead (@NWSMoreheadCity) June 18, 2025
Along the East Coast, highs will soar to 90 degrees or hotter as far north as at least the nation’s capital and Baltimore. Much of the Mid-Atlantic will be in the major HeatRisk category, level three out of four, today. This level of heat is "dangerous to anyone without proper hydration or adequate cooling," according to the National Weather Service.
Elevated fire weather conditions are forecast today for parts of the Pacific Northwest, including eastern Washington and northeastern Oregon. The SPC says “a belt of strong midlevel westerly flow will overspread the Cascades,” and relative humidity as low as 20 to 25 percent will bring about the elevated risk in this region.