Schoolchildren across England and Wales lost more than 15 million hours of teaching time during June’s heatwave, according to new research.
The study, conducted by investigative outlet DeSmog, reveals at least 760,000 pupils missed lessons as soaring temperatures forced more than 1,700 schools to close completely or shorten their opening hours.
Record-breaking June temperatures caused conditions inside some classrooms to top an “unbearable” 40C, triggering widespread cases of heat stress, nausea, and fainting among pupils and staff.
The research shows direct school closures accounted for roughly 5.9 million lost learning hours, while heat-related pupil absences at schools which remained open caused a further 9.5 million missed hours.
On the hottest days of the heatwave, student absence rates spiked sharply, reaching double the annual average across regions in southern England and climbing above 36 per cent in Wales.
Teaching staff reported extreme indoor heat rendered effective learning nearly impossible, with educators describing classrooms where pupils required assistance for heat exhaustion and dehydration.
Education experts have warned heat-induced closures risk worsening attainment gaps, particularly for students from disadvantaged backgrounds who rely on schools for structured learning, social support, and free meals.
Charlotte O’Regan, schools engagement lead at the Sutton Trust, pointed to pandemic-era disruption as evidence warned that closures risk compounding educational inequality for vulnerable students.
“School closures can put students in the most deprived areas at a disadvantage, and heat-related closures risk doing the same,” Ms O’Regan said. “Not only are these pupils less likely to have costly cooling systems in their home, but they also often have insufficient resources at home to support their learning.”
She added state school leaders face severe budget constraints when attempting to adapt classrooms for climate extremes.
“While some schools or parent organisations are able to pay to ensure that their environments are suitable for study, we know that state school leaders are already having to face difficult decisions when it comes to funding,” Ms O’Regan said.
“We saw a significant widening of the attainment gap during the pandemic, and we have to make sure that the weather doesn’t become yet another barrier holding back those worst off.”
A Department for Education spokesperson defended the response to the weather conditions, arguing schools successfully mitigated the impact.
“Hot weather can be a struggle, but schools did a fantastic job keeping children learning safely during this summer’s heatwave,” the spokesperson said.
“Schools put measures in place, so they remained the best place for children to be, even during a heatwave – because every day in school counts,” they added. “Where schools remained open, nine in 10 pupils attended as normal, as teachers pulled out all the stops to keep classrooms cool and children learning.”
Campaigners and teaching representatives have urged ministers to increase funding for infrastructure adaptations, including improved ventilation, thermal shading, and building upgrades, to prevent future heat disruption.
Climate scientists have warned the disruption this summer will rapidly become the new baseline as global warming interacts with intensifying natural climate cycles.
The onset of strong El Niño weather patterns — which supercharge global sea and atmospheric temperatures — is projected to push UK summer extremes even higher, converting once-rare 35C-plus heat events into routine occurrences.
With the UK’s ageing school infrastructure largely unequipped to handle prolonged extreme heat, experts warn that without significant structural retrofitting, heatwaves will cause recurring, multi-week disruptions to the academic calendar every year.
