GRAND RAPIDS, Mich. (AP) — Summer-like heat caused the closing of public schools Thursday and Friday in Michigan’s second-largest city and shorter class days in Detroit.

High temperatures of 90 were predicted across the southern Lower Peninsula.

“That not only makes the learning environment a challenge, but it also raises a safety concern,” said Leadriane Roby, superintendent in Grand Rapids.

Some Grand Rapids schools in western Michigan don’t have air conditioning. There are about 13,750 students.

In Detroit, the school day was cut by three hours Thursday and Friday because of heat. The district has roughly 48,000 students.