Unusually high temperatures are snarling the early school year, causing more schools in the Northeast to cut short or even stop classes because it's too hot.
Schools in states including Michigan, Maryland, Pennsylvania and New Jersey cut classes short or switched to online instruction. In Massachusetts, one district has canceled classes for two days.
Temperatures reached the mid 90s Fahrenheit in Pittsburgh and Baltimore; in Detroit temperatures peaked at 89 degrees on Tuesday.
Schools say they don't have the air conditioning needed to counter days of extreme heat, or say they need to repair and update power grids to handle the load of more climate control.
One government estimate from 2020 showed there were some 36,000 schools nationwide that needed to update or install HVAC systems.
"We never want to inconvenience our families with early releases, but we also do not want our staff and students to be so uncomfortable that teaching and learning becomes a distraction to the heat," Detroit Public Schools said in a statement.
Other schools, including in Ohio, announced closures immediately following the Labor Day weekend due to the extreme heat.
Schools close for extreme heat as many lack air conditioning
Dozens of school districts throughout the U.S. are closed due to extreme heat, placing parents in a continuous lurch.
In places, the late summer highs have been more than 10 degrees above average. The new school year is also coming as the world ends the hottest July and August of modern record-keeping.
The extreme temperatures are a symptom of fossil emission-driven climate change, scientists say. Experts warn extreme temperature events are likely to become more common as long as fossil emissions continue.