Milwaukee, Wisconsin – Southern Wisconsin is preparing for a rapid return of summer heat and humidity after a relatively mild stretch, while isolated severe thunderstorms remain possible through the weekend and into Monday.
According to the National Weather Service in Milwaukee/Sullivan, isolated thunderstorms may develop across north-central Wisconsin between 2 p.m. and 6 p.m. Saturday before tracking southeast. Most storms are expected to weaken before reaching southern Wisconsin, but an isolated severe storm cannot be ruled out across northwestern portions of the area between 6 p.m. and 10 p.m. If storms hold together, damaging wind gusts and large hail would be the primary hazards.
The greater concern arrives Sunday and Monday as temperatures and humidity climb sharply. Widespread heat index values between 95 and 103 degrees are expected during the hottest part of each day, generally from noon until 7 p.m. Heat advisories may be needed as conditions become increasingly uncomfortable.
Cities including Milwaukee, Madison, Kenosha, Racine, Janesville, Waukesha, West Bend, Beaver Dam, Fond du Lac and Sheboygan are expected to experience heat index values near or above 100 degrees. Madison, Janesville, Sauk City and Whitewater could see peak heat index readings around 102 to 103 degrees, while Milwaukee is forecast to reach around 101 degrees.
According to the National Weather Service, the atmosphere will remain favorable for severe thunderstorm development Sunday and Monday wherever storms form, although confidence in exactly where storms develop remains low. Damaging winds and large hail are expected to be the primary hazards, with an isolated tornado also possible. Some communities may remain completely storm-free while others experience rapidly developing severe weather.
Residents should stay hydrated, limit strenuous outdoor activities during the afternoon, and check for updated forecasts before making outdoor plans. Have multiple ways to receive weather warnings, especially Sunday and Monday when storms could develop quickly alongside dangerous heat.
Warnings, heat advisories and additional severe weather outlooks may be issued through early next week as the pattern evolves.
