It’s always hot in the summer in the U.S. Southeast, but even by the standards of Florida and the Carolinas, the steamy heat wave on tap for the region Saturday into the coming week is a little extreme.

The National Weather Service issued heat advisories for a large swath of the East Coast from central Florida to Virginia through much of the weekend. Highs in the upper 90s F (mid 30s C) were forecast for central Florida, with heat indexes reaching 105 degrees F to 110 degrees F (40.6 C to 43 C). The outlook was similar up through Georgia and the Carolinas into Virginia.

Extreme heat warnings were out for much of eastern North Carolina, as far inland as Raleigh, and extending into a corner of South Carolina, including Myrtle Beach. Forecasters warned of dangerously hot conditions with temperatures approaching or exceeding 100 F (38 C) in some areas on Sunday and heat indexes up to 115 F through Sunday evening.

“Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. the weather service advised. “Take extra precautions when outside. Wear lightweight and loose fitting clothing. Try to limit strenuous activities to early morning or evening. Take action when you see symptoms of heat exhaustion and heat stroke. Stay cool, stay hydrated, stay informed.”

The weather service said several major metropolitan areas in the Southeast — including Raleigh and Charlotte in North Carolina, Greenville-Spartanburg in South Carolina, and Atlanta in Georgia — were expected to face an extreme heat risk for several days, with minimal overnight relief. It said over 30 million people would likely be affected at the peak of the heat wave through midweek.

A hot, humid weekend was also in store for the Midwest. Extreme heat watches were out for eastern Nebraska, western Iowa and southern Minnesota. Heat indexes were expected to reach 96 F (36 C) on Saturday and go even higher on Sunday in Minnesota.

And an extreme heat warning was out for the St. Louis, Missouri, area through Tuesday evening, with highs around 99 F (37 C) and heat indexes around 110 F forecast for Monday and Tuesday.

Parts of Iowa were hit by storms Saturday morning that dumped between 2 and 5 inches (5 to 13 centimeters) of rain in some areas and triggered flash flood warnings.