Much of the midwestern and southern United States braced for a potentially dangerous and fatal heat wave Tuesday, with temperatures that could reach records in some places and combined with humidity could feel like 38 Celsius (100 Fahrenheit) or more.

More than 100,000 people are expected to be affected by the middle of the week, and authorities have warned residents to drink plenty of water, stay indoors when possible and be aware of the risks of high temperatures. Severe storms brought downpours and high winds to many of the affected areas on Monday and more than 500,000 users were still without power as of Tuesday morning.

Excessive heat warnings were in effect for much of Illinois and Indiana, along with parts of southern Michigan and northwestern Ohio from Tuesday morning through Wednesday night, the National Weather Service said.

Wind chill — which takes into account temperature and relative humidity and indicates how it feels to be outside — could reach 40.5 Celsius (105 F), the service said.

“Full sun today will make it even hotter,” he said. “There won’t be much relief for those without air conditioning between now and Wednesday.”

Much of southern Michigan — from south of Flint to the Ohio and Indiana state lines — was under an excessive heat watch Wednesday through Thursday morning as the wave moved east.

A heat advisory was also issued from Wisconsin, to the north, to the Florida territorial arm, on the coast of the Gulf of Mexico.

In Chicago, where an intense storm Monday night preceded temperatures expected to exceed 32 Celsius (90 F) on Tuesday and Wednesday, the May deaths of three women when temperatures reached those levels served as a reminder of the dangers of such heat — especially for people who live alone or with health problems.

Categorized in: