More districts across the country are modifying schedules this week as broken or nonexistent cooling systems fail to keep buildings cool.

School districts in Illinois, Indiana, Iowa, Missouri, Ohio, Wisconsin and other states have either closed or dismissed students early as the National Weather Service said millions of people are being affected by excessive heat. The agency said the record-breaking heat is bringing highs well into the 90s, and 100s in some places with humidity.

The National Weather Service said heat will likely blanket the Midwest and Gulf region well into Friday, during what it called a heat dome. The temperatures are "extremely anomalous" and likely to break daily and monthly records, the service said.

Thousands of schools need updated HVAC systems

A U.S. Government Accountability Office study from June 2020 report found more than 36,000 schools needs updates or replacements to their HVAC systems.

Last year, schools in Detroit, Philadelphia and Baltimore let students out early or closed as record-high temperatures hit those states. Experts then said many schools aren't equipped to battle with the extreme weather threats brought by climate change.

A study in 2021 from the Center for Climate Integrity found more than 13,700 K-12 public schools that didn't need cooling systems in 1970 will need them by 2025. New York City, the nation's largest school district, must spend up to $1 billion in ventilation system costs by 2025 because of climate change, according to the study. 

Heat threats school operations:Hotter temperatures a threat to students in schools with no air conditioning

Shain Bergan, spokesman for Kansas City Public Schools in Missouri, told USA TODAY all of the district's buildings have some form of cooling systems, but not all classrooms are cool. He added the district has tried and failed to pass a bond referendum to install central air.

School districts in the middle of the country could soon be forced to adapt to heat-related schedule changes, he said.

"We're all used to winter weather impacting the schools and it could be a thing where summer weather will impact schools. I hope not," Bergan said.

What schools are closed, dismissing early this week?

Nationwide, school officials said they are worried about high temperatures.

Milwaukee Public Schools announced it closed for a second time in a week with temperatures predicted to reach 115 degrees. The Lockland School District in Ohio canceled classes for grades fifth through 12th grades this week because the buildings lacked air conditioning. In Indiana, the Downers Grove Grade School District 58 Superintendent Kevin Russell announced Monday the district delayed its first day of school to Friday because of the heat and Whitko Community Schools' Junior Senior High School is doing remote learning because of air conditioning repairs.

The Decorah Community School District in northern Iowa canceled classes Thursday as Superintendent Tim Cronin said staff were concerned about high temperatures at one of its elementary schools.

Elsewhere in the country, Kansas City Public Schools in Missouri, Grand Haven Area Public Schools in Michigan and Robertson County Schools in Tennessee announced early dismissals because of the heat and humidity. Bergan said it's tough to change schedules during the first week, but the 100-degree heat index creates unique problems for staff and students.

Spokesman of Robertson County Schools Jim Bellis said the district has modified its schedule as it is trying to protect students as much as possible. He added all buildings have HVAC units.

Four school districts throughout Iowa are letting students out early this week. The National Weather Service said late Wednesday Des Moines set a record-high temperature of 100 degrees. Des Moines Public Schools has air conditioning but is still dismissing students early because school buses lacked air conditioning, along with the neighboring Johnston Community School District. Interstate 35 Community School District in southern Iowa and Charles City Community School District in northern Iowa both had early dismissals this week.

Teachers unions say it is too hot

Teachers at Milwaukee Public Schools in Wisconsin and Polk County Public Schools in Florida have urged their districts to either update or install cooling units. The Wisconsin teachers union made their request in 2021 as readings reached 90 degrees and Superintendent Milwaukee Public Schools Keith Posely said he'd make it a priority for the district's COVID-19 relief money, but that didn't happen.

Only 17% of buildings had air conditioning throughout the building, Posely said, 63% had it in one room and 20% had no air conditioning at all.

The teachers union in Polk County, Florida, filed a grievance with the district, claiming at least 15 schools have faulty air conditioning units. Kyle Kennedy, senior coordinator of media relations for the district, said in a statement the district typically receives an influx of work orders when staff returns and this year's has been exacerbated by a heat wave.

The School District of Philadelphia Chief Operating Officer Oz Hill told USA TODAY the district has invested $285.7 million in its HVAC systems. He said more than 800 window units and 1,400 cold-water drinking stations have been installed.

The district hadn't issued closures this year because it moved the start date after Labor Day from late August to avoid heat-related interruptions. Spokesperson Monique Braxton said half of the buildings don't have adequate cooling systems and the district is "rigorously" reviewing all of them.

Contributing: Tiffany Cussac-Smith, USA TODAY; Rory Linnane, Milwaukee Journal Sentinel; Phillip Sitter, Philip Joens; Des Moines Register; Paul Nutcher, Lakeland Ledger.

Contact reporter Krystal Nurse at knurse@USATODAY.com. Follow her on X, the platform formerly known as Twitter @KrystalRNurse.

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