The largest school district in Ohio canceled all classes and after-school activities on Tuesday because of scorching temperatures in the usually mild Midwest.

Columbus city schools announced the closure on their website, saying classes were called off because of “heat and humidity” on Oct. 1.

Temps in the city of about 880,000 people are expected to reach up to 94 degrees on Tuesday, topping the previous record in the month of October by three degrees, television station WCPO reported.

About a third of school buildings in the city don’t have air conditioning, according to the report.

The closure comes as a heatwave is poised to sock large swaths of the Midwest, according to the Weather Channel.

Louisville, Nashville, Memphis and Cincinnati could all register temperatures in the 90s this week, beating previous records, the Weather Channel reported.