A heat-dome-driven furnace that will grip most of the southern UK
Across England and Wales, a second major heatwave of 2026 is unfolding — not merely as a repetition of May's heat, but as something qualitatively different. A humid heat dome drifting north from France is saturating the air with moisture, rendering the body's own cooling systems ineffective and pushing 'feels like' temperatures to 41 degrees Celsius even where thermometers read 35. What distinguishes this event most profoundly is the absence of relief: consecutive tropical nights deny the body its nightly recovery, compounding a stress that climate scientists warn will only grow more familiar as a warming atmosphere holds ever more moisture.
- A static heat dome of subtropical origin has locked over the UK, pulling moist south-easterly winds that make 35°C feel like 41°C — a gap that separates discomfort from genuine danger.
- Unlike the bone-dry 2022 record heatwave, this event's high humidity disables the body's primary defence: sweat cannot evaporate, and the cooling mechanism simply fails.
- Three to four consecutive tropical nights — temperatures refusing to fall below 20–23°C — are compounding the crisis, denying sleep and allowing cardiovascular and heat stress to accumulate day after day.
- Records are already falling: Wales set a new overnight minimum this week, and Thursday night threatens to break June minimum temperature records across Wales, the Midlands, and the South East.
- Health authorities are raising particular alarm for elderly and vulnerable populations, for whom the unrelenting combination of humid days and sleepless nights can escalate rapidly from exhaustion to acute crisis.
- Climate scientists are unambiguous: a warmer atmosphere holds more moisture, and without sharp emissions reductions, heatwaves of this humid, punishing character will return with growing frequency and severity.
England and Wales are enduring their second major heatwave of the year, and this one carries a sting that raw temperature figures alone cannot convey. Where forecasts show 35 degrees Celsius, the air will feel closer to 41. That gap is not a rounding error — it is the difference between uncomfortable and genuinely dangerous.
The cause is a heat dome that originated in the hot, humid subtropics and drifted north from France, where temperatures have already exceeded 40 degrees. As it shifted, it drew south-easterly winds laden with moisture. Dr. Akshay Deoras of the University of Reading describes the result as not merely a heatwave but a heat-dome-driven furnace. The physics are straightforward: sweat cools the body only when it can evaporate, and saturated air prevents that. The body's primary cooling mechanism fails, and the 'feels like' temperature climbs well beyond what thermometers record.
The comparison to July 2022 — when the UK recorded 40 degrees for the first time — is telling. That event was brutal in its numbers, but the air was dry. This June's heatwave, with lower headline temperatures and far higher humidity, will likely feel worse and carry greater health consequences.
What makes this event especially punishing is the absence of overnight relief. Many locations will not cool below 20 degrees Celsius — tropical nights — and some may experience three or four in succession. During 2022, most places saw at most two back-to-back. When the body cannot recover between daytime heat spikes, cumulative stress compounds: sleep deteriorates, cardiovascular strain builds, and heat exhaustion becomes more likely even in otherwise healthy people. For the elderly and those with existing conditions, the risk becomes acute. Thursday night may see the warmest June minimum on record across Wales, the Midlands, and the South East, with some locations potentially exceeding records set as recently as this week.
Dr. Deoras is direct about the trajectory: a warming atmosphere holds more moisture, and this combination of rising heat and rising humidity will make such events more frequent and more intense. The question is no longer whether heatwaves like this will return, but how often, and how severe.
England and Wales are bracing for the second major heatwave of the year, and this one carries a particular sting. Thermometers will climb into the mid-to-high 30s Celsius over the coming days—territory the region visited just weeks ago in May. But raw temperature tells only part of the story. Where the forecast shows 35 degrees, the air will feel closer to 41. The difference between those two numbers is the difference between uncomfortable and genuinely dangerous.
The culprit is a static mass of high pressure—what meteorologists call a heat dome—that has settled over the region with unusual stubbornness. Unlike May's heatwave, when this dome sat directly over the UK, this one originated in the hot, humid subtropics and has drifted north from France, where temperatures have already soared past 40 degrees. As it has shifted, it has pulled a south-easterly wind that carries with it air saturated with moisture. Dr. Akshay Deoras, a senior research scientist at the University of Reading, describes it bluntly: not merely a heatwave, but a heat-dome-driven furnace that will push temperatures into truly exceptional territory.
The physics of why this feels so much worse than the May event comes down to humidity's effect on the human body. When we sweat in hot weather, that moisture evaporating from our skin is what actually cools us down. But when the air is already thick with moisture, sweat cannot evaporate effectively. The body's primary cooling mechanism simply fails. Meteorologists can calculate this mismatch between actual temperature and perceived temperature—the "feels like" number—by combining air temperature with humidity levels. A 35-degree day with high moisture content will genuinely feel like 41 degrees to anyone living through it.
The comparison to the historic July 2022 heatwave, when the UK recorded 40 degrees for the first time, is instructive. That event was brutal by the numbers, but the air was bone-dry. This June's heatwave, with lower headline temperatures but far higher humidity, will likely feel worse and carry greater health consequences. The moisture in the air amplifies heat stress on the body in ways that dry heat does not.
What makes this event particularly punishing is what happens after sunset. Overnight temperatures will barely drop. Many locations will not cool below 20 degrees Celsius—what meteorologists call tropical nights. Some areas may experience three or four such nights in succession, a pattern rare in previous UK heatwaves. During the 2022 event, most places saw at most two tropical nights back-to-back. The difference is crucial: when the body cannot cool down between daytime heat spikes, the cumulative stress compounds. Poor sleep follows. Cardiovascular strain builds. Heat exhaustion becomes more likely, even in people who are generally healthy. For vulnerable populations—the elderly, those with existing health conditions—the risk becomes acute.
Thursday night may see the warmest June minimum temperature on record across Wales, the Midlands, and the South East, with lows between 21 and 23 degrees Celsius. Some locations could exceed the current UK record of 22.7 degrees set in 1976, or Wales's record of 20.3 degrees, which was only set this week. Even at the coolest part of the night, the "feels like" temperature may hover around 27 degrees.
Dr. Deoras warns that this pattern will become the new normal unless emissions fall sharply. A warming atmosphere holds more moisture. The combination of rising temperatures and rising humidity will make heatwaves like this one more frequent and more intense. The question is no longer whether such events will return, but how often, and how severe they will become.
Citações Notáveis
This is not just a heatwave, it is a heat-dome driven furnace that will grip most of the southern UK and push temperatures into truly exceptional territory.— Dr. Akshay Deoras, University of Reading
A warmer atmosphere holds more moisture, so the combination of increased temperatures and humidity is what is likely to make humid heatwaves like this become more frequent and more intense.— Dr. Akshay Deoras, University of Reading
A Conversa do Hearth Outra perspectiva sobre a história
Why does this heatwave feel worse when the temperatures are actually lower than 2022?
Because humidity is doing the work that heat alone didn't have to do before. In 2022, the air was dry—your sweat could evaporate and cool you. Now the air is saturated. Your body's cooling system gets stuck.
So it's not just about the number on the thermometer.
Not at all. The thermometer is almost beside the point. What matters is whether your body can shed heat. High humidity locks that heat in.
You mentioned tropical nights. Why are consecutive ones so dangerous?
Because your body never recovers. You're stressed all day, you can't cool down at night, and then the stress starts again. Over three or four nights, that accumulation becomes serious—even for healthy people.
Is this a one-time event, or a sign of something larger?
It's a sign. As the planet warms, the atmosphere holds more moisture. We'll see more of these humid heatwaves, and they'll be worse each time unless we cut emissions drastically.
What makes this heat dome different from the one in May?
The May dome sat right over us, so heat built up underneath it. This one came from the humid subtropics and drifted north from France. It's pulling moist air in from the southeast instead of trapping dry air overhead.
Who's most at risk?
Vulnerable people—elderly, those with heart conditions. But that's the thing: this humidity is dangerous enough that healthy people are at real risk too. It's not just a problem for the already fragile.