Ideally, you’re able to take children out at times to have that gross motor play — that important time where they’re able to get those zoomies out. But if you don’t have adequate shade, and it’s hot and getting hotter, then you actually can’t take your children outside. It changes what the learning environment looks like for the day to day and creates more stress on educators to ensure that they have what they need to keep their children safe.¹

In August of 2025, just as schools were about to open their doors for the Fall semester, experts gathered at Harvard to discuss the issue of extreme heat and K-12 education. As heat waves become more common across the US, educators are calling attention to this under-recognized threat to children’s health.

For school leaders navigating this reality, extreme heat represents more than an inconvenience—it’s an urgent crisis demanding immediate attention and strategic planning. As heat waves creep north, they are baking schools that previously did not need air conditioning, forcing districts nationwide to confront a growing threat to student health, academic achievement, and educational equity.

Key steps school leaders can take to address extreme heat situations include modifying outdoor activities and schedules, ensuring access to hydration, improving school facilities for cooling, and establishing heat protocols for school staff.

Defining the Danger: What Constitutes Extreme Heat for US Schools?

Extreme heat isn’t simply a hot day that makes everyone uncomfortable. From a public health perspective, extreme heat refers to temperatures that significantly exceed the average maximum temperature for a specific location and time of year, typically lasting two or more days. For schoolchildren, this definition becomes particularly critical given their unique physiological vulnerabilities.

Children’s smaller bodies heat up more quickly than adults, making them particularly susceptible to heat-related health impacts. Their bodies also have more difficulty regulating temperature, meaning what might be uncomfortable for an adult can become dangerous for a child.

For U.S. schools, extreme heat warnings typically trigger action when outdoor temperatures reach levels that could cause heat exhaustion or heat stroke in children engaged in normal school activities. This threshold varies significantly across the country—from 85°F in traditionally cooler northern states to 95°F or higher in southern regions—with humidity levels playing a crucial role in determining actual risk.

The Academic Cost: How Heat Undermines American Education

The impact of extreme heat on American students extends far beyond physical discomfort, creating measurable declines in academic performance that threaten educational outcomes nationwide. Research examining student performance reveals alarming trends: In school districts without air conditioning, a 1℉ increase in average school year temperature is associated with a 1 percent decline in learning.²

This academic impact isn’t theoretical—it’s happening in classrooms across the country right now. When temperatures soar, students struggle to concentrate, become irritable, and experience reduced memory retention. Teachers find themselves constantly monitoring student wellness rather than delivering curriculum, fundamentally altering the learning environment that millions of children depend on.

The physiological stress of extreme heat also creates cascading effects throughout the school day. Students arrive at school already depleted from walking or waiting at bus stops in excessive heat. Playground activities become dangerous, forcing schools to cancel recess and physical education—critical components of children’s development and learning. Lunch periods move indoors to overcrowded cafeterias, creating additional stress and reducing the restorative break students need.

Heat waves also disrupt attendance patterns across American schools. When classroom temperatures become unbearable, parents keep children home, creating gaps in learning that compound over time. For students already facing educational challenges, these heat-related absences exacerbate existing achievement gaps that American schools are working to close.

The Infrastructure Crisis: America’s Cooling Divide

Perhaps most troubling is how extreme heat exposes and worsens existing educational inequities across school districts. The statistics paint a stark picture of unpreparedness: About 1 in 5 California schools has no air conditioning, while classes have resumed in many districts around the country that have outdated heating and cooling systems — or no air conditioning at all.

This infrastructure crisis isn’t distributed equally across American schools. Affluent districts often operate newer buildings with modern HVAC systems, adequate insulation, and backup cooling measures. These schools can maintain comfortable learning environments even during heat waves, allowing education to continue with minimal disruption. In contrast, under-resourced districts frequently operate in older buildings with outdated or insufficient cooling systems, poor insulation, and limited financial resources to upgrade infrastructure.

The disparity becomes particularly stark in urban areas where schools serving predominantly low-income students and students of color are more likely to lack adequate cooling. Underfunded schools struggle to keep cool as aging systems break down and heat intensifies, creating a two-tiered system where zip code determines whether students can learn in comfort and safety.

Rural American schools face their own unique challenges, often operating in aging buildings designed primarily for heating during harsh winters but lacking adequate cooling capacity for increasingly hot summers. Limited budgets and geographic isolation make infrastructure improvements more difficult and expensive, leaving these communities particularly vulnerable to heat-related disruptions.

The data reveals just how widespread this problem has become. Even in traditionally cooler regions, schools are struggling as climate patterns shift. Northern districts that historically never needed extensive cooling systems now find themselves unprepared for sustained heat waves that arrive earlier and last longer than in previous decades.

A Growing Crisis

The data surrounding extreme heat and American schools reveals a system under increasing pressure. About 2,300 people in the United States died in the summer of 2023 with their death certificates mentioning the effects of excessive heat. That’s the highest in 45 years of records, underscoring the deadly seriousness of rising temperatures across the country.

For schools, this translates into an urgent operational challenge. Heat waves are becoming more frequent and intense, with government data showing increases in heat-related deaths as temperatures continue to rise. School districts that once experienced occasional hot days now face extended periods of dangerous heat that disrupt entire academic calendars.

The back-to-school season has become particularly challenging, as children start the school year, concerns about rising heat in classrooms continue. Many districts have already begun adjusting their academic calendars, starting school later in the year, implementing more frequent breaks during peak heat periods, or investing in temporary cooling solutions.

The Path Forward: Strategic Leadership for America’s Schools

For American school leaders, addressing extreme heat requires both immediate action and long-term strategic planning tailored to local conditions and community needs. Hot classrooms are highly detrimental to student learning. In school buildings without working HVAC systems, they are also a public health issue, making this both an educational and safety imperative.

Successful heat mitigation strategies begin with honest assessments of current building conditions and cooling capacity. Leaders must prioritize infrastructure investments, seeking federal and state funding opportunities specifically designed for climate resilience improvements. The American Rescue Plan Act and other federal programs have provided unprecedented opportunities for school infrastructure upgrades, including HVAC improvements, but these monies are no longer available.

Equally important is developing comprehensive heat emergency protocols tailored to local conditions. This includes training staff to recognize heat-related illness symptoms, establishing clear communication channels with families and community partners, and creating flexible scheduling options for extreme heat days. Some districts have pioneered innovative solutions, from installing temporary cooling systems to partnering with community organizations to provide alternative cool spaces.

Facing the Challenge

The challenge of extreme heat in American schools is not a distant future concern—it’s a present reality demanding immediate attention from educational leaders across the country. As temperatures continue to rise and heat waves become more frequent and intense, the schools that fail to adapt will find themselves unable to fulfill their fundamental mission of providing safe, effective education for all students.

In terms of practical steps, school leaders can:

1. Modify Outdoor Activities and Schedules

• Limit or reschedule strenuous outdoor activities to cooler times of the day, such as before 11 a.m. or after 4 p.m.
• Move recess, sports, and physical education classes indoors when temperatures and UV radiation are at their peak.
• Consider early dismissal or staggered schedules on extreme heat days.

2. Ensure Access to Hydration

• Provide and encourage frequent drinking of water; install or increase the number of water fountains or coolers throughout the school.
• Integrate regular water breaks into the school day, particularly for young children who may not recognize when they need to drink fluids.

3. Improve School Facilities for Cooling

• Retrofit buildings with energy-efficient air conditioning and improve ventilation.
• Install shade structures in outdoor play areas and use trees, awnings, or canopies to increase shaded space.
• Use water misters or coolers in playgrounds, and avoid surfaces that absorb and radiate heat, such as blacktop; favor natural or reflective surfaces when possible.

4. Educate and Establish Heat Protocols

• Train staff on the signs and symptoms of heat-related illnesses and first aid procedures.
• Develop or review clear heat emergency policies, including defined thresholds for modifying activities or dismissing students early.
• Promote appropriate dress codes for extreme heat, such as lightweight, loose-fitting, and light-colored clothing.

Implementing these solutions can help schools safeguard children’s health, comfort, and learning during periods of extreme heat.

^[1] Keeping kids safe in extreme heat. Experts outline threats to childhood development, school challenges, play-time risks.

^[2] When the heat is on, student learning suffers

Leslie Stebbins is the director of Research4Ed. She has more than twenty-five years of experience in higher education and K-12 learning and instructional design. She has an M.Ed. from the Technology Innovation & Education Program at the Harvard Graduate School of Education and a Master’s in Library and Information Science from Simmons College.