In June 2026, more than 1,000 UK schools closed, partially or fully, on a single day because of record heat. It made headlines and it probably made staffrooms tense. But, it reignited a question that comes round every summer now: is this actually a new problem, or is one hot week just one hot week?

It’s a fair question. A single scorching June doesn’t prove much on its own, as we know. So what would actually be convincing? Is this a serious question?

One hot month isn’t the evidence. The pattern is.

I did get one suprise when I started reseraching this: 2025 tied with 1933 and 1992 for the most individual UK heatwave spells on record. If you only looked at that one number, you’d conclude nothing much has changed since the 1930s. But the heat wave count is the wrong thing to look at in isolation. What’s actually convincing isn’t the single year records, it’s several separate measures all moving the same direction, decade on decade:

• The number of UK days over 30°C has roughly trebled over recent decades
• A 40°C day is now more than 20 times more likely than it was in the 1960s
• The last three years have been the UK’s hottest on record
• 2026 was the first year on record with 35°C+ readings in May, June, and July, three separate months.

That’s the actual pattern worth putting in front of a governor or a head: not “look how hot last week was,” but “look at what’s true across the last ten years, measured five different ways.” A decade of hot-day counts trending the same way across independent metrics is data.

So is it real, or is this a moral panic?

Working in climate education – you realise it’s worth taking the skeptical view seriously rather than waving it away. There’s a reasonable strand of criticism, some of it aimed squarely at how the Met Office and the media frame heat records, arguing that year-to-year weather variability is genuinely huge, that “hottest since records began” headlines can shout louder than what the underlying statistics really show, and that 1976 and 1995 remind us extreme UK summers aren’t a new invention.

And so the case for “this is real” doesn’t actually rest on press releases or a single dramatic headline. It rests on several unrelated fields independently landing on the same conclusion, using completely different data and methods: Met Office climate attribution studies, World Health Organisation thermal comfort research, and education economics papers out of Japan, the US and the UK all separately link rising heat to measurable effects on learning. When fields that have no reason to agree with each other all point the same way, that’s a stronger signal than any one heatwave stat, or headline.

Why this matters for your Climate Action Plan

Adaptation and resilience, planning for the physical risks a changing climate brings, is one of the four required areas in every school’s Climate Action Plan, alongside decarbonisation. Heat days sit inside that category – it’s not a side issue – but it is one of the more immediate, visible risk.

The health case is also serious. An estimated 2,700 excess deaths were recorded across England and Wales during the May and June 2026 heatwaves alone. Children are more vulnerable than adults in heat specifically, because their bodies regulate temperature less efficiently and they dehydrate faster, which is why schools are a meaningful place to plan for this.

Are these numbers are concrete enough to put in front of decision-makers directly? Research modelling UK exam conditions found pupils were around 10% less likely to pass an exam sat at 32°C compared with 22°C. That’s not a vague “children find it harder to concentrate,” it’s an outcome tied to a specific, rising number of days a year.

What this means for your classroom, right now

The evidence case matters for planning ahead, but heat days also need a same-day response. A few headline points:

• Ventilation timing matters more than people think: windows open early, before the room heats up, closed once outdoor air is warmer than indoor air
• Uniform and activity adjustments (loosening dress code, swapping vigorous PE for something sedentary) do more for comfort than people expect
• Watching for early signs of heat exhaustion in pupils matters more than watching a thermometer; there’s no legal maximum classroom temperature to trigger action automatically

For the full practical breakdown, ventilation, uniform, hydration, what the DfE guidance actually says, see our earlier post, Schools in the Heat: Practical Tips for Hot Weather.