DES MOINES, Iowa (AP) — Summer camp and other outdoor activities were canceled or delayed Monday as a heat wave held its grip on the Midwest and spread eastward. Communities opened cooling centers and urged people to take it easy and stay hydrated.

“Overall, we’re looking at just a really hot and humid pattern. It’s going to be with us through most of the week,” Andrew Ansorge, a meteorologist in Des Moines, Iowa, said of the first prolonged period of heat this summer.