More than 300,000 students will return to classrooms in sweltering heat on Monday as the first day of school begins in Chicago public schools.

The first day of the 2024-25 school year began a week later than usual due to the Democratic National Convention, which was held August 19-22 at the United Center and McCormick Place in Chicago.

According to the National Weather Service, a heat advisory for Cook County with “dangerously hot conditions” will go into effect at noon on Monday. Heat index values ​​between 103 and 107 degrees were expected for Monday, with even hotter values ​​expected on Tuesday, according to the NWS.

While all CPS classrooms have air conditioning, many buildings do not have central air conditioning, meaning hallways and gymnasiums can be hot. Slides, swings and other playground equipment can also be dangerously hot to the touch, experts warned.

“Hydration, hydration, hydration. Make sure your kids have a water bottle with them and are taking small sips throughout the day,” said Dr. Juanita Mora, national medical spokeswoman for the American Lung Association. “Snacks are good and hydrating, also give them a small pack of grapes or sliced ​​oranges with them… Don’t give them sugary drinks like Gatorade, Kool Aid or Capri Suns. They’re full of sugar and not particularly hydrating.”

MORE: 4 easy and quick ways to cool down your body in extreme heat

A letter was sent to CPS families over the weekend outlining the district’s efforts to keep students and staff cool and safe despite the warning of excessive heat.

According to CPS, all outdoor sports games and competitions will be canceled on Monday and Tuesday due to the heat. All outdoor practices will also be moved indoors or canceled, officials said.

All classrooms are equipped with air conditioning for instruction, and building technicians will ensure that any air conditioning systems that experience problems are repaired quickly, the letter said.

Teachers may be asked to pull down blinds to block out sunlight and keep doors closed in rooms where window air conditioners are used.

Finally, all non-essential lights, computers and devices will be turned off when they are not needed for instruction.

CPS has also sent notices to families about bus transportation as the district continues to negotiate with unions representing school bus drivers.

“Chicago Public Schools (CPS) is one of many school districts across the country that has experienced a shortage of individuals interested in becoming school bus drivers in recent years,” the statement said. “This national shortage has forced CPS to prioritize yellow bus transportation for our most at-risk students – our eligible students with disabilities and students in temporary living situations (STLS), two demographic groups that are also both growing in size.”

“As a district, we remain committed to addressing the impacts of this bus driver shortage and have deployed many strategies to address it, from increased driver wages to continued advocacy for appropriate state testing and certification requirements,” the letter continued.

Heat warnings, advisories, observations Monday and Tuesday for the Chicago area

Highs of 96 degrees were expected for Monday, with a feel of 100-105 degrees, said NBC-5 meteorologist Kevin Jeanes. Tuesday is expected to be even hotter, with highs of 98 degrees and a heat index of up to 110 degrees.

According to the NBC 5 Storm Team, the record high for Monday and Tuesday was 97 degrees, set in 1972.

“Be prepared to drink plenty of fluids, stay in air-conditioned rooms, avoid the sun and check on relatives and neighbors,” the NWS warned. “Small children and pets should never be left unattended in vehicles under any circumstances. This is especially true in warm or hot weather when temperatures inside a car can become fatal within minutes.”

“This is the hottest air we’ve seen so far this summer,” the NWS said in a message posted on X, the platform formerly known as Twitter.

Monday’s weather also comes with an air quality warning for all of northeastern Illinois, the NWS said. Air quality is expected to reach “unhealthy levels for sensitive groups,” which is a level two out of five.

The warning is expected to last “at least until Monday,” the NWS said.

Tuesday’s forecast includes the possibility of thunderstorms early in the morning and evening, Jeanes said, with northern Illinois having a “minor” risk of severe weather, rated as a level one out of five on the Storm Prediction Center’s scale. Isolated storms that develop could include lightning strikes, heavy downpours and gusty, destructive winds, the NWS said.

According to the Office of Emergency Management and Communications, 250 cooling centers across the city of Chicago were scheduled to be activated on Monday and Tuesday.

Temperatures on Wednesday and Thursday are expected to be in the upper 30s, although humidity will remain high and the chance of storms will remain, Jeanes said. Temperatures will drop again to just above 80 degrees and above 75 degrees over Labor Day weekend, Jeanes added.