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Access to cooling is critical to ensure the health, safety, and well-being of students and school staff in our rapidly warming world.

from Climate Central

August 27, 2025

Students across the country will soon head back to school — and in some cities, class has already been in session for weeks. In many places, summer heat lingers as students and staff begin a new school year.

As the planet warms, higher average temperatures and more frequent extreme heat increase the cooling demand to keep homes, schools, and other buildings at safe, comfortable temperatures.

Extreme heat affects children's health, development, and behavior. It can also impact students' ability to concentrate and learn. One study found that a 1°F hotter school year is associated with a 1% reduction in learning that year, based on test scores — but air conditioning can offset heat-related impacts to learning.

A lack of air conditioning in schools is more than just uncomfortable. Extreme heat is the deadliest weather-related hazard in the U.S., and children are among those most vulnerable to heat-related illness. Access to air conditioned spaces provide children with a safe place to cool down after spending time playing outdoors in hot weather.

Cooling demand is reflected in a temperature-based metric called cooling degree days (CDD). CDD values estimate how much cooling is needed to maintain a comfortable indoor air temperature. 

• CDD values are the difference between a location’s daily average outdoor temperature and 65°F, an engineering standard that is considered the ideal indoor temperature.
• For example, a day with an average temperature of 90°F has 25 CDD (90°- 65°). 

CDD values are highest on the hottest days of the year. But any day over 65°F — including warm late summer and early fall days during the back-to-school season — has some need for cooling. 

Keeping schools cool is a growing challenge as our climate warms and many places experience hotter summers and shoulder seasons.

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