CHICAGO (CBS) — As the heat ratchets up above 100 degrees Thursday, the Chicago Public Schools are canceling classes in 12 buildings that do not have working air conditioning.

CBS 2 Meteorologist Mary Kay Kleist says the high Thursday will likely hit 100 degrees. As of 5 a.m., it was already 77 degrees at O’Hare International Airport.

With summer classes being held in some schools that lack air conditioning, CPS has decided to cancel classes at those schools as a precaution.

“Due to reports of excessive heat throughout Chicago tomorrow, we have determined that it is in the best interest of our students and instructional staff to cancel summer school for the day in non-air conditioned buildings,” Chicago Public Schools chief executive officer Jean-Claude Brizard said in a news release.

The schools that will close include:

• Altgeld Elementary, 1340 W. 71st St.;
• Attucks Elementary, 5055 S. State St.;
• Bennett Elementary, 10115 S. Prairie Ave.;
• Courtenay Elementary Language Arts Center, 1726 W. Berteau Ave.;
• Faraday Elementary, 3250 W. Monroe St.;
• Gregory Math and Science Academy, 3715 W. Polk St.;
• Holden Elementary, 1104 W. 31st St.;
• Jahn World Language School, 3149 N. Wolcott Ave.;
• Penn Elementary, 1616 S. Avers Ave.;
• Pope Elementary, 1852 S. Albany Ave.;
• Stevenson Elementary, 8010 S. Kostner Ave.;
• Harold Washington Elementary, 9130 S. University Ave.

The Chicago Public Schools will monitor the heat and provide additional information through its Web site, cps.edu, as well as Facebook and Twitter.