The National Weather Service is warning that the Independence Day weekend will bring dangerous heat across the Midwest, with heat indices forecast to reach or exceed 100°F in parts of Illinois, Wisconsin and Minnesota. Afternoon temperatures are expected to climb into the upper 80s and low 90s, but high humidity will push the perceived heat well higher, prompting advisories for those planning outdoor celebrations. Forecasters also anticipate scattered thunderstorms from Friday through Sunday. Isolated storms could form north of Interstate 90 in northern Illinois on Friday morning, followed by a more widespread round Sunday afternoon. The Weather Prediction Center cautions that some storms may generate damaging wind gusts, torrential rain and localized flash flooding, particularly in the Upper Midwest and central Plains. Unsettled conditions extend beyond the Midwest. The Weather Prediction Center projects heavy rain for much of the central and southern United States and additional downpours in the Northern Rockies and Florida. Central Texas broadcasters have issued a Weather Impact Alert for Friday because of gusty winds and lightning, while moisture over Arizona’s higher terrain is expected to spark afternoon storms. Authorities urge travelers to stay hydrated, seek shade when possible and monitor updated forecasts throughout the holiday period.