HINDMAN, Ky. — Withering heat was descending on a region of eastern Kentucky already reeling from massive flooding, forcing residents laboring to clean up after the deluge to cope with an oppressive new threat.

The grim task of cleaning up from the flooding continued, but rising heat and humidity prompted officials to open cooling centers Tuesday as forecasters warned of the risk of heat-related illnesses and some residents remained without power.

The blast of heat and humidity comes as some residents try to salvage what they can, and as search-and-rescue crews continued looking for people unaccounted for days since the floods hit.

“Extreme heat, extreme humidity, that’s stressful in itself," said Jerry Stacy, the emergency management director in hard-hit Perry County, Kentucky. “We’re just fighting through this and hoping that this weather don’t make it too stressful. It don’t get a lot worse than what it is.”

A heat advisory was issued for flood-ravaged regions of eastern Kentucky from midday Wednesday until Thursday evening, with heat index readings expected to approach triple digits, the National Weather Service said.

“We’ve got to make sure that those that are vulnerable either have a cool place with family ... or that we get them to cooling stations," Kentucky Gov. Andy Beshear said Tuesday. “We didn’t make it through the worst flooding that we have ever seen in our lifetime to lose somebody now in the heat."

The death toll stood at 37 on Tuesday after more bodies were found Monday in the devastated landscape, and while more than 1,300 people have been rescued, crews were still trying to reach some people who remain cut off by floods or mudslides.

“It is absolutely devastating out there," Beshear said. "It’s going to take years to rebuild. People left with absolutely nothing. Homes that we don’t know where they are, just entirely gone. And we continue to find bodies of our brothers and sisters that we have lost.”

On a positive note, Beshear said most of the people reported as missing to Kentucky State Police had been found and that cellphone service had been restored though much of the region.

Meanwhile, he warned Kentuckians to be mindful of the heat as the cleanup continues.

“I know you may be out there working to salvage whatever you can. But be really careful Wednesday and Thursday when it gets hot,” he said. "We’re bringing in water by the truckloads. We’re going to make sure we have enough for you. But you’re going to need a cool place at least to take a break.”

For hundreds of people whose homes were damaged or destroyed, that place was an emergency shelter. As of Tuesday, nearly 430 people were staying at 11 such shelters, and 191 more were being housed temporarily in state parks, Beshear said.

Meanwhile, the flooding has forced some eastern Kentucky districts to delay the start of school. Several schools in the region were damaged, officials said, and the focus now is on helping families whose homes were damaged or destroyed.

“Just that in and of itself is going to take time before we can even start the conversation with the community about where kids are going to go to school,” said John Jett, superintendent in Perry County, where classes were supposed to start Aug. 11 but have been delayed.

Two of the Perry County district’s nine schools suffered severe damage and one will likely have to be rebuilt because of a partial collapse, he said.

In Knott County, Superintendent Brent Hoover said classes would be delayed until the district can assess damage at the high school, an elementary school and the technology center. In Letcher County, Superintendent Denise Yonts said six of the district’s 10 schools were damaged by flooding and two staff members died. The district is committed to getting students back into classrooms as soon as possible to restore some sense of normalcy, she said.

“Our community as a whole is devastated,” Yonts said.

President Joe Biden declared a federal disaster to direct relief money to counties flooded after 8 to 10 1/2 inches (20 to 27 centimeters) of rain fell in just 48 hours in parts of eastern Kentucky, southern West Virginia and western Virginia.

The Associated Press contributed to this report. Follow along below for the latest updates on recovery in Eastern Kentucky.