A woman sits in the shade to avoid the heat Monday in Detroit. (AP Photo/Paul Sancya)

Another week of blistering heat will bring even more health risks in the coming days, as overnight temperatures won’t provide much relief.

The National Weather Service is predicting more than 90 temperature records across the U.S. will be tied or broken this week through Wednesday — and most of those will be overnight heat records.

The unofficial high in Iron Mountain on Monday was 100 degrees F, according to Accuweather, which while not a new record for July 13 — that would be 103 degrees in 1936 — is the first time since 2006 the city has reached a triple-digit temperature, NWS records show.

The NWS’s extreme heat warning remains in effect until 9 p.m. Central/10 p.m. Eastern time today.

Health experts warn overnight temperatures that fail to cool down are even more dangerous than daytime temperatures that soar.

It has already been a sweltering start to the summer across much of the U.S. due to the long-lasting heat dome expected to blanket much of the country this week. The blistering temperatures over the past few weeks have caused heat-related deaths in New Jersey and helped fuel wildfires in the West.

Temperatures were not forecast to drop below 80 F at night in Fort Lauderdale, Florida; Miami; Tampa, Florida; Galveston, Texas; and Charleston, South Carolina, the National Weather Service said.

Over the next few days, places in the Midwest and Northeast known for frigid winters will see nighttime temperatures remain above 70 F, including Fargo, North Dakota; International Falls, Minnesota; and Portland, Maine.

Health experts say that high overnight temperatures are particularly dangerous because there’s no time for the body’s core temperature to cool down and recover from daytime heat.

“That’s where the health outcomes are amplified, particularly for the elderly and vulnerable communities,” said University of Georgia meteorology professor Marshall Shepherd.

Just a few degrees of increased body temperature can lead to heatstroke or put too much strain on the heart.

If temperatures at night don’t cool down your body, the health risks more often show up the next day, said Kristie Ebi, a public health and climate scientist at the University of Washington.

“Mortality starts the second or third day” because the body’s unable to cool, she said Monday.

Early warning signs include heavy sweating, muscle cramps and headache. “It’s hard to know you’re getting in trouble with the heat. This is why we need to be more proactive,” Ebi said.

It’s important to find a way to cool off, whether stepping into air conditioning or wrapping a cold towel around your neck.

And health experts say don’t forget to check in on friends and family members, especially those who are older, pregnant or who have health challenges that might make it more difficult to handle the heat.

Even without air conditioning at home, there are ways to find relief.

Stop by a library or a mall. Sit in front of a fan and spray water on your skin. Put your feet in cold water. Soak your clothes in water. And of course, drink plenty of water.

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Associated Press reporter Seth Borenstein in Washington contributed to this report, as did Daily News staff.