DES MOINES, Iowa (AP) — Summer camps and other outdoor activities were canceled Monday as tens of millions of people across the Midwest endured a heat wave that is expected to spread eastward this week. Communities opened cooling centers and urged people to take it easy and stay hydrated.

Forty-seven million people across big chunks of the Midwest and parts of the Ohio Valley are under an extreme heat warning through at least Tuesday. Temperatures are forecast to reach the 90s, with heat index values, or “feels-like” temperatures, expected to top 100 degrees (37.8 degrees Celsius) in the region, according to the National Weather Service.

Visiting Des Moines with family, Rachel Washburn searched for things to do with kids during a heat wave. They landed at a water sprayground before lunch Monday, where her children played tag in the cool water.

“My kids were quite shocked at the heat and humidity,” said Washburn of her seven children ages 18 months to 17 who had been used to more temperate weather farther north in Bemidji, Minnesota. “We were hoping for some good weather, but we'll make do.”

About 56 million Americans are under an extreme heat watch as hot and humid weather is expected to move farther east later in the week, with some of the worst conditions expected by Thursday and Friday in the Ohio Valley, the Mid-Atlantic and into the Northeast. Some areas could experience record-high temperatures, said Scott Kleebauer, a meteorologist with the Weather Prediction Center in College Park, Maryland.

On Monday, cities and event planners were already announcing adjustments for or calling off events later in the week, including a farmer's market scheduled for Tuesday in DeWitt, Michigan; a movie screening Wednesday in Fairfield, Ohio; and Thursday’s food truck festival in Warwick, New York.

The heat wave will also likely coincide with the Fourth of July holiday weekend, providing additional risk as more people have cookouts or watch fireworks outside for the 250th anniversary of American independence.

Kleebauer said the center recommends people stay hydrated and ensure access to shady areas and air conditioning.

Emergency workers were out in Nashville on Monday to offer water and check on people during the hottest time of the day.

Mike Russell, a captain at the Nashville Office of Emergency Management, said he saw many empty areas where people typically sleep outside, which he said was a good sign that they found someplace cool to escape the heat for a while.

Logan King, 29, brought a cart to fill up on cold water and snacks when the emergency workers came out to a patch of woods behind a Walmart where he and others sleep outside. The trees where people have pitched tents offer some cover from the direct sun, but not much relief.

“It’s just miserable honestly, but this helps so much,” King said. “Even with the shade and a tent ... it gets hot."

Extreme heat has also taken its toll in Europe, where temperature records were set and many heat-related deaths were reported in France.

People can be caught off guard by the first heat wave of the year, said Dr. Roy Elrod, chief of staff at DMC Detroit Receiving Hospital.

“You’re happy winter’s gone, you’re ready to enjoy the summer, you’ve just been aching for it,” Elrod said. “And so, I think we slip into kind of a position where we think it’s got to be OK.”

Heat-related injuries can happen in a matter of minutes, he said, especially to those who don’t prepare for the weather by hydrating, wearing light clothing, avoiding the hottest times of the day and minimizing exposure to the sun.

The University of Wisconsin-Madison said it was closing 23 buildings to the public starting Tuesday, allowing only limited access to 11 others. It was relocating some summer classes after a broken water line at its cooling plant earlier this month severely reduced the ability to provide air conditioning across campus.

Temperatures approaching 90 degrees and high humidity didn’t stop Toni Kreutzer, 28, from taking a walk Monday along the shores of Lake Mendota in Madison, Wisconsin, with her 13-year-old dog Chester.

“I like it hot,” Kreutzer said. "I just don’t like the humidity."

McCormack reported from Concord, New Hampshire. Associated Press reporters Scott Bauer in Madison, Wisconsin, Kristin M. Hall in Nashville and Haya Panjwani in Washington, D.C., contributed. This story was published originally by the Associated Press. The Associated Press is an independent global news organization dedicated to factual reporting. Founded in 1846, AP today remains the most trusted source of fast, accurate, unbiased news in all formats and the essential provider of the technology and services vital to the news business. Read the original article at: https://apnews.com/article/heat-wave-weather-warning-midwest-northeast-a47b8a4c9e74f7708309cd4af0fcd1c7