CHICAGO (CBS) — With Monday likely to be the hottest day of the year so far, many schools that have already started the new school year have adjusted their schedules to get kids out of class early.

The temperature was expected to reach 92 degrees, which would make it the hottest day of the year. The previous high was 91, on June 17.

The heat index on Monday was expected to reach as high as 105 degrees in much of the Chicago area.

If you happen to attend one of the many schools in Chicagoland that isn’t entirely air-conditioned, Monday promises to be a tough one.

That’s the case at Roosevelt Middle School in River Forest. Only about a third of the classrooms in the River Forest Public Schools District 90 are air-conditioned, so the word of the day at school on Monday was hydration.

Students were encouraged to bring water bottles, and were taking frequent breaks.

“The air-conditioned rooms are our largest rooms in the building. We do a pretty nice job at having pretty heavy-duty blowers blowing the cold air into the warmer areas of the school,” principal Larry Garstki said. “We started that last spring, and it’s worked out actually very nicely.”

In Waukegan Public School District 60, students started classes earlier than normal, and were scheduled for earlier dismissal as well, in hope of missing what is typically the hottest part of the day.

That’s also the plan at public schools in Grayslake and Beecher. One parochial school in Beecher closed entirely due to the heat.