Severe Expected Likely Extreme Heat Warning Extreme Heat Warning issued June 29 at 5:52PM CDT until June 30 at 7:00PM CDT by NWS Green Bay WI Jun 29, 5:52 PM → Jun 30, 7:00 PM WHAT: Dangerously hot conditions with heat index values up to 109expected. Overnight heat indices will remain around 75 degrees,which will still be hazardous for anyone without shelter after theextreme heat in the afternoon. WHERE: Marathon, Portage, Waushara, Wood, Calumet, Winnebago,Brown, Outagamie, Shawano, and Waupaca Counties. WHEN: Until 7 PM CDT Tuesday. IMPACTS: Heat related illnesses increase significantly duringextreme heat and high humidity events. + Read More Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Updated: Jun 29, 11:10 PM Source: NWS Alert