Heat Is Quietly Rewriting the School Day, Threatening Learning and Health Across the United States
Extreme heat is emerging as one of the most consequential—and least visible—threats facing schools in the United States. As heat waves become more frequent, last longer and reach higher temperatures, students and educators are spending more time in environments that can undermine concentration, physical health and emotional well-being. A new report from the American Psychological Association and the Network for Resilient PK–12 Schools in Extreme Climates warns that schools must treat extreme heat as a central educational and public-health challenge rather than as an occasional disruption. The report, Schools, Climate, and Health: Responding to Extreme Heat, synthesizes research on how high temperatures affect learning, behavior and the body, while outlining how districts can prepare for a hotter future.
The risk is intensified by the amount of time children and school employees spend in buildings, outdoors and in transit during the hottest parts of the day and year. Many schools, particularly older buildings and those serving communities with fewer financial resources, lack effective air-conditioning, adequate ventilation or properly designed cooling systems. Heat can accumulate inside classrooms through a process known as heat storage, in which walls, roofs, windows and furnishings absorb solar energy and gradually release it into occupied spaces. Indoor temperatures may therefore remain dangerously high even after outdoor conditions begin to improve. Students may also face heat exposure while walking, waiting for buses, participating in physical education or attending sports and after-school programs.
The human body maintains its internal temperature through thermoregulation, a coordinated process involving blood flow, sweating, cardiovascular activity and signals from the brain. During extreme heat, blood vessels near the skin expand to release heat, while sweat evaporates from the skin and carries thermal energy away from the body. High humidity interferes with this mechanism by reducing the difference in moisture between the skin and surrounding air, making evaporation less efficient. Children are particularly vulnerable because their bodies can produce and regulate heat differently from adults, and younger students may not recognize or communicate early symptoms. Dehydration, dizziness, nausea, headache and weakness can develop quickly, especially when heat exposure is combined with physical exertion.
Heat stress does not stop at immediate physical symptoms. Prolonged exposure can place sustained demands on the cardiovascular system, which must circulate more blood toward the skin while maintaining adequate supply to the brain and other organs. Research cited in the report indicates that heat can elevate stress hormones, disturb sleep, increase inflammation and impair cardiovascular and immune functioning. These physiological effects matter in schools because learning depends on a body and brain capable of maintaining attention over long periods. Poor sleep caused by hot nights can further reduce alertness, working memory and emotional regulation the following day, creating a chain reaction in which heat exposure outside school hours amplifies the effects of overheated classrooms.
The cognitive consequences are especially important because education depends on complex mental operations that are highly sensitive to stress and fatigue. Attention requires the brain to filter distractions and sustain focus, while working memory allows students to hold and manipulate information during reading, problem-solving and instruction. When the body is overheated, physiological resources are redirected toward cooling and maintaining circulation. Discomfort and thirst also compete for attention, increasing the mental effort required to perform ordinary academic tasks. Studies have reported lower test scores among students on hot school days, suggesting that heat can affect not only how students feel but also how they perform when assessed. The report describes heat as a potential “snow day for cognition,” emphasizing that a classroom may remain open while the conditions needed for effective learning are compromised.
The impact is unlikely to be evenly distributed. Low-income families and communities with fewer resources may be more exposed to poorly cooled homes, older school buildings, limited transportation options and reduced access to medical care. Students with chronic health conditions, disabilities or heightened sensitivity to heat may face additional risks, as may young children whose communication and self-monitoring skills are still developing. Outdoor activities, athletics and commuting can add short periods of intense exposure to the cumulative burden of an already overheated day. Because these vulnerabilities overlap with existing educational inequalities, extreme heat may widen achievement gaps by imposing the greatest physiological and cognitive costs on students who already face the fewest protections.
Mental health is another area of concern. Heat exposure has been associated in research with increased emergency department visits for mood disorders, self-harm and suicidal behavior among children and adolescents. Such findings do not mean that heat alone causes a particular mental-health crisis; psychological outcomes are shaped by many interacting factors, including sleep disruption, air pollution, social stress and access to care. However, heat can act as an additional biological and environmental stressor. Higher temperatures may influence sleep, inflammation, neurotransmitter activity and irritability, while uncomfortable conditions can intensify conflict and reduce the ability to regulate emotions. In a school setting, these effects may appear as restlessness, disengagement, anxiety, aggression or difficulty recovering from ordinary frustrations.
Educators are also exposed to the same conditions, often while managing crowded classrooms and maintaining instructional demands. Prolonged heat stress has been linked to physical, cognitive and emotional exhaustion, a combination that can impair decision-making and communication and contribute over time to burnout. Teachers working in overheated rooms may have less capacity to deliver demanding lessons, monitor student well-being or respond calmly to behavioral challenges. The report therefore frames heat protection as a whole-school issue rather than a matter of student comfort. Districts are urged to establish clear leadership and accountability for heat planning, define temperature or heat-index thresholds, monitor conditions and connect heat procedures to emergency and safety plans instead of relying on informal judgment.
Effective protection requires action at multiple levels. Schools can prioritize cooling improvements in buildings and neighborhoods where heat causes the greatest harm, while ensuring that vulnerable students and staff receive automatic protection rather than having to request accommodations. Districts can create specific rules for athletics, extracurricular activities, transportation and after-school programs, where exposure may occur outside ordinary classroom hours. They can coordinate plans with families and caregivers, communicate heat warnings clearly and adjust schedules, instructional loads and assessment dates when conditions threaten cognition. Hydration, light clothing and personal behavior remain useful, but the report emphasizes that these measures should be the final layer of protection, not the primary defense. Structural solutions—including shaded outdoor areas, efficient cooling, ventilation, reflective surfaces and reliable transportation procedures—are more dependable than expecting individuals to adapt indefinitely.
The report’s central message is that extreme heat is no longer a distant climate projection or a rare interruption to the academic calendar. It is already influencing the environments in which students learn and educators work, with consequences that reach from dehydration and exhaustion to test performance, mental health and educational equity. By recognizing heat as a threat to both physiology and cognition, schools can move beyond reactive closures and develop systems that protect learning before conditions become dangerous. The American Psychological Association says the recommendations are intended to help districts create safer, healthier environments as heat intensifies across the country. The report was developed by a network that includes public-health, environmental-health, education, parent and psychological organizations, making it an unusually broad call for schools to prepare for a hotter era.
Subject of Research: The effects of extreme heat on student learning, physical health, mental health, educator well-being and school safety in the United States.
Article Title: Heat Is Quietly Rewriting the School Day, Threatening Learning and Health Across the United States
Web References: https://www.apa.org/pubs/reports/schools-climate-health/extreme-heat-matters
References: Schools, Climate, and Health: Responding to Extreme Heat, American Psychological Association and the Network for Resilient PK–12 Schools in Extreme Climates.
Keywords: extreme heat, heat waves, schools, student health, learning, cognition, mental health, educators, climate change, public health, heat stress, education equity
