This year, record-breaking heatwaves are upending school routines across U.S. cities. In the wake of one of the hottest summers on record, school districts nationwide are grappling with extreme heat during back-to-school season. Cities like New York, Philadelphia, and Detroit have faced days so hot that traditional schedules became untenable. With many aging school buildings lacking air conditioning, administrators have been delaying start times, dismissing students early, and even considering overhauls to the academic calendar to keep children safe. Without action, students — particularly those in underserved communities — face unsafe learning environments that hinder their health and education.

In this article, we explore what triggered these drastic measures, the background factors at play, the impact on students and schools, and the consequences and adaptations underway. We also discuss what to expect going forward as climate change continues to intensify extreme heat, and how schools and parents can respond.

What Triggered the School Calendar Overhauls?

Record Heatwaves and Aging Infrastructure

The immediate trigger for recent school schedule overhauls has been a series of record-breaking heatwaves striking at the start of the school year. Summer 2025 was among the hottest ever recorded, and dangerously high temperatures bled into August and September – the months when American students traditionally return to classrooms. Unbearably hot days are no longer confined to summer vacation; even in northeastern cities and the Midwest, early fall heat surges have become more frequent.

Millions brace for extreme temperatures across US – ABC News

Crucially, many school buildings were not built for this climate. Most American schools were constructed for a cooler era and lack modern cooling systems. A 2020 Government Accountability Office survey found 41% of U.S. school districts needed to update or replace HVAC systems in at least half their schools – roughly 36,000 buildings. In regions historically mild in late summer, air conditioning was seen as optional. Now, those same classrooms can reach sweltering temperatures that make teaching and learning impossible. “You can’t satisfactorily, in any way, shape or form, actually teach if it’s above 90 degrees in a classroom, never mind learn,” said New York State Senator James Skoufis, who noted that until recently there was no legal maximum classroom temperature on the books.

City Spotlights: New York, Philadelphia, Detroit

The past two school years have provided stark examples. New York City officials, during a June 2025 heatwave, urged schools to move end-of-year activities indoors to escape the heat. In Philadelphia, the school district had to dismiss students early at more than 60 campuses in late August 2024 because those buildings lacked adequate air conditioning. Meanwhile, Detroit Public Schools saw heat index values climb so high during the first week of the 2024–25 year that they cut school days short for all 52,000 students. Detroit’s district has a policy to release students early whenever the city’s heat index hits 90°F, which was tripped on those scorching late-August days.

These scenarios underscore a dangerous combination of extreme weather and outdated infrastructure. When outdoor heat pushes indoor classroom temperatures into the upper 80s or 90s (°F), schools without adequate cooling have little choice but to send kids home early or cancel classes. In June 2025, even parts of upstate New York and traditionally cool regions faced heat indices over 100°F, prompting half-day schedules in districts around Buffalo, Rochester, and Syracuse. It’s a nationwide problem: in over 230 U.S. cities, the demand for cooling in schools during back-to-school season has risen significantly since 1970, a trend scientists attribute to climate change. Simply put, today’s climate is overpowering yesterday’s school calendar.

Impact on Students and Learning

Health Risks and Unsafe Classrooms

For students, especially young children, extreme heat isn’t just uncomfortable – it can be dangerous. Children’s bodies heat up faster than adults’, making them especially vulnerable to heat-related illnesses. In overheated schools, kids and staff have experienced asthma attacks, fainting, nosebleeds, and even heat exhaustion symptoms. School nurses and teachers report that some students become physically ill – vomiting or suffering from headaches – when trapped in sweltering classrooms. Beyond acute illness, research shows heatwaves can heighten anxiety and distraction in children. It’s no surprise that federal health guidance lists children among those at highest risk during extreme heat and urges schools to limit strenuous activity and ensure hydration on hot days.

Critically, overheated classrooms are also ineffective learning environments. Cognitive scientists and education researchers have found that as temperatures rise, students’ ability to focus and retain new information plummets. A 2020 study that tracked 16 years of test scores alongside weather data revealed a troubling link: high schoolers who experienced an abnormal number of hot days scored worse on standardized tests (like the PSAT) compared to peers who had cooler school years. The researchers concluded that even a 1°F increase in average school-year temperature can reduce learning by about 1% for that year. Over time, these heat-induced learning losses stack up, potentially affecting graduation rates and long-term outcomes.

Underserved Communities Hit Hardest

Extreme heat in schools is also an equity issue. Students in underserved communities often attend older, under-resourced school buildings with inadequate HVAC systems. They are disproportionately bearing the brunt of these heat disruptions. Nationwide data from 2024–2025 shows hotter temperatures contributed to higher rates of school absences, particularly for Black, Hispanic, and low-income students. Many families face a cruel dilemma on hot days: send children to a stifling classroom or keep them home (where they may lack supervision or a quiet place to study). In practice, students from low-income households often opt to stay home on the hottest days rather than risk sitting in a sweltering school. This means missed class time and further learning gaps.

Compounding the issue, the same children who attend schools without AC are more likely to live in homes without air conditioning. In Detroit, for example, 7% of the city’s residents – including 15% of Black families – have no air conditioning at home, according to the U.S. Census. For these students, an early dismissal doesn’t necessarily bring relief: they may go from an overheated school to an overheated house. “One of my biggest concerns is that many kids who lack AC in their schools also don’t have it at home,” noted Kristen Hengtgen of UndauntedK12, a nonprofit focused on climate-resilient schools. The evenings meant for homework and restful sleep can be just as stifling, further eroding learning. “Learning doesn’t end when kids leave school… so much of the processing of what they learn happens when they’re asleep,” explains Dr. Lindsey Burghardt of Harvard’s Center on the Developing Child, emphasizing that hot, sleepless nights can undo daytime learning.

Nena Kae scrambled for a way to get herself, her kindergartener, and her 3-year-old, Mahkell Kae, home after an unexpected early school day release at Barton Elementary School due to extreme heat on Aug. 27, 2024. (Jena Brooker / BridgeDetroit)

The result is a widening achievement gap. Because Black and Hispanic students are the least likely to have air conditioning at school and at home, researchers estimate that extreme heat accounts for roughly 5% of the racial academic achievement gap in the United States. In other words, heat inequity is directly translating into education inequity. It’s an alarming statistic that underlines how climate change is not only an environmental and public health issue, but also a matter of educational justice.

How Schools Are Adapting to Extreme Heat

Emergency Measures: Early Dismissals and Delayed Start Times

Faced with immediate heat crises, many school districts have resorted to emergency scheduling changes. Early dismissals on extremely hot days have become common in districts from the Northeast to the Midwest. For example, Philadelphia’s public schools, recognizing dozens of their buildings could not safely host students in 90°F+ heat, dismissed 63 schools three hours early during a late-August 2024 heatwave. In Detroit’s first week of school 2024, all schools operated on half-days for multiple days, with students released roughly 3 hours early to beat the worst afternoon heat. Some upstate New York districts likewise announced half-days and delayed start times when a heatwave hit in June 2025. These stopgap measures prioritize student safety – a school can’t function if dozens of kids are feeling faint – but they also sacrifice valuable instructional time.

In some cases, schools have even preemptively closed campuses or shifted to remote instruction during heatwaves. In Pittsburgh, where many schools are nearly a century old with no central AC, the district activated an “extreme heat protocol” in June 2023. On two 90°F days, students at 40 Pittsburgh schools were switched to remote learning from home rather than attend dangerously hot buildings. A message to Pittsburgh families explained that if classroom temperatures are forecast above 85°F, schools may “shift… to remote learning” or take other actions. This was a striking decision – effectively treating extreme heat like a snowstorm by declaring a virtual learning day. It shows how districts are dusting off the remote-teaching capabilities honed during the pandemic to cope with climate-related disruptions. “As we enter the summer months, it was important to establish an extreme heat protocol for our facilities without sufficient air conditioning,” Pittsburgh’s superintendent said, noting that this transparency helps families plan and allows instruction to continue virtually.

Rethinking the Traditional Academic Calendar

Beyond day-to-day tweaks, broader calendar overhauls are now on the table. Many educators and policymakers are asking tough questions: If August and September are becoming as hot as July, should the school year be adjusted? Some have even floated the once-unthinkable idea of shifting summer break to cooler months. “There’s even some talk of replacing summer vacation with a spring or fall break, if schools can be kept cool enough,” reports The Guardian. The logic is provocative: instead of taking off July and August (which are increasingly plagued by extreme heat), students might attend school during those months in air-conditioned classrooms, and take their long break in, say, October or April when the weather is milder. This would require massive operational changes and investments in cooling – most schools “are not built for that” yet, as climate and health researcher Grace Wickerson points out. “It’s definitely a needed conversation,” Wickerson says, “especially since we’re already seeing school days canceled or moved around [due to heat].” If extreme heat continues to worsen, what once sounded blasphemous to tradition – holding school in mid-summer – could become a serious option.

Already, the school calendar is shifting in subtle ways. In warmer regions, some districts are building “heat days” into their academic calendars (much like snow days) or pushing back start dates. The nation’s largest school system, New York City, moved its first day of school in 2023 to after Labor Day, partly to avoid the late-August heat – a notable change from previous years. And as mentioned, schools are increasingly treating heat waves as an emergency akin to winter storms, with makeup days or virtual learning filling the gaps.

Policy Responses and Infrastructure Investments

Policymakers have started to respond to these challenges. New York State recently became the first in the nation to pass a law setting heat standards for schools. Taking effect on September 1, 2025, the law establishes 88°F as the maximum allowable temperature in any occupied classroom. If indoor temps reach 82°F, schools are now required to take action – whether that means relocating students to cooler areas, deploying cooling equipment, or dismissing early. “For as long as anyone could remember, we had a minimum classroom temperature (65°F) but no maximum,” Senator Skoufis (the bill’s sponsor) explained. “You can’t…actually teach if it’s above 90 degrees in a classroom.” New York’s law compels schools to proactively monitor heat conditions and is likely a model other states will examine as they face similar predicaments.

At the federal level, there is growing recognition of the climate adaptation gap in education. Last summer, 22 organizations (including the Federation of American Scientists) sent a letter urging the U.S. Department of Education to take swift action to protect students from rising temperatures. The Biden Administration has directed some funding towards school infrastructure upgrades – for instance, nearly $10 billion from the 2021 American Rescue Plan is earmarked for modernizing HVAC systems in schools. However, the need is far greater. Experts estimate it would cost about $40 billion to install adequate cooling in every American school that lacks it. In other words, current funds address only a quarter of the problem. “If you draw a line across the U.S. at roughly Washington D.C.’s latitude, everything north of that line was not built with air conditioning in mind,” notes engineering professor Paul Chinowsky, emphasizing the vast retrofitting challenge ahead.

Some districts aren’t waiting for outside help. Detroit’s school district is investing $125 million to install or upgrade air conditioning in 90% of its school buildings by 2030. This is a significant commitment, considering fewer than half of Detroit schools currently have AC. Still, that leaves the hottest, oldest 10% of schools in question – officials admit those may eventually need to be phased out if they can’t be cost-effectively cooled. Other cities, like Philadelphia, have accelerated installation of window AC units and chillers in some buildings after high-profile complaints, but progress is uneven. Greening schoolyards is another strategy: planting trees for shade and replacing heat-trapping blacktop with grass can lower ambient temperatures for outdoor spaces. Experts recommend aiming for 30% tree canopy coverage around schools, yet a recent survey found California schools have a median of just 6.4% – highlighting room for improvement nationwide.

Bill Uhrich/MediaNews Group/Reading Eagle via Getty Images

The consequences of inaction are clear: more broken-up school days, more health incidents, more learning loss, and widening inequities. Conversely, the benefits of action are significant. Studies show that cooling classrooms yields academic gains – for instance, lowering a class’s temperature from 86°F to 68°F was found to improve students’ performance by 20%. “Can you imagine if there was another school intervention that had that much impact? We’d be all over it,” Dr. Burghardt quipped, noting that investing in climate-resilient schools is ultimately an investment in children’s futures. In short, every dollar spent on air conditioning, ventilation, and heat preparedness can pay dividends in student well-being and achievement.

What to Expect in the Future

As global temperatures continue to rise, educators and parents should prepare for the “new normal” of hot school days. Climate projections suggest that what we now consider unusual heat may soon be commonplace. In one analysis, Detroit’s frequency of 90°F+ school days could quadruple in the next 25 years if greenhouse gas emissions continue unabated. Likewise, experts at Ten Strands (an environmental education nonprofit) warn that “the average number of days hitting 87°F is increasing every year, and is estimated to reach 120 days a year by the 2030s.” That implies nearly one-third of the year could be too hot for a school without cooling to operate normally. Other U.S. regions face similar trends, meaning heat-related disruptions might shift from exceptional to routine.

In response, we should expect to see more schools and states taking adaptive measures. This could include formalizing “heat days” with plans for remote learning, much like many districts do for snow days. School calendars might start earlier in the summer and include longer breaks in early fall, or vice versa, as communities experiment with minimizing student exposure to peak heat. We may also see technology playing a larger role – from smart thermostats and heat sensors in classrooms to district-wide emergency alert systems that pivot to online lessons when needed. The conversation around year-round schooling or relocating summer break will likely gain momentum if high temperatures keep rendering July and August unusable for outdoor play or even indoor learning without AC. “Is it safer to keep kids in adequately cooled schools during extreme heat, or let them stay home?” one report mused, capturing the tough questions educators are now facing.

On the infrastructure side, the coming years should bring significant upgrades. School boards are increasingly factoring climate resilience into their capital plans. That means not only air conditioning installations, but also better insulation, reflective roofing, improved ventilation, and greener campuses. Policymakers might channel more funds into programs that support energy-efficient school improvements, given the economic and educational payoff of climate-proofing schools. There is also likely to be a push for data collection and standards – as one expert noted, it’s hard to fix what isn’t measured. We may soon see requirements for schools to report indoor climate conditions and for states to establish heat safety standards (following New York’s pioneering example).

In sum, extreme heat is now a critical factor in education planning. Schools that never needed cooling must adapt or face repeated disruptions. Parents will need to stay alert to heat advisories and emergency school communications, just as they do for snowstorms. And students, unfortunately, will need resilience – whether that means doing homework at a cooling center or wearing lighter uniforms – as we collectively navigate the challenges of a warming world. The encouraging news is that awareness is growing, and with it, a determination to innovate. As Detroit teacher union president Lakia Wilson-Lumpkins put it bluntly when explaining the district’s heat-driven early dismissals: “It’s climate change.” A growing chorus of educators and parents understand that reality and are asking, “What can we do to ensure our kids keep learning, no matter the weather?”

Ensuring Continuity of Education – How AHS Can Help

When heat waves or other extreme weather threaten to disrupt learning, having a robust contingency for remote education can make all the difference. This is where AHS Education comes in as an invaluable resource for schools and families. AHS is a modern online learning platform offering free, high-quality K–5 curriculum and interactive lessons that align with U.S. state standards. By leveraging AHS, schools and parents can ensure that students continue to access quality education regardless of the situation – whether it’s an early dismissal for heat or a prolonged facility closure.

For school administrators, AHS provides a turnkey solution to keep students engaged from home on unscheduled days off. Instead of losing entire days of instruction to heat closures, districts can use AHS’s digital lessons to maintain momentum. The platform includes interactive videos, worksheets, and progress tracking, allowing teachers to monitor student work remotely. AHS can be integrated into an extreme heat protocol as the go-to virtual classroom, so learning seamlessly transitions online when buildings get too hot. This not only protects students’ health but also prevents learning loss during heatwaves.

For parents, AHS offers peace of mind that your child’s education won’t be put on pause due to weather or other disruptions. Parents can sign up for free and access a wealth of engaging educational content for their kids. The lessons are self-paced and student-friendly, featuring story-based cartoon adventures and quizzes that make learning fun (even without direct teacher supervision). Importantly, AHS has options for families with limited internet access as well – including downloadable content and offline worksheets – ensuring that underserved communities can benefit fully. By using AHS at home, parents can turn an early dismissal day or heat-related school cancellation into an opportunity for continuous learning in a safe, cool environment.

Don’t let extreme heat derail your child’s education. Schools and parents can be proactive by incorporating AHS into their contingency plans. Every student deserves a consistent, high-quality learning experience, even when climate disruptions occur. AHS is committed to providing that stability and excellence in education without boundaries.

Get Started with AHS: Schools interested in exploring AHS can sign up for a free demo to see how the platform can integrate with their curriculum and emergency plans. Parents can sign up for free to give their children access to AHS’s interactive learning resources at home. With AHS, we can ensure that no matter how extreme the weather gets, our students keep growing, learning, and succeeding — safely and comfortably.