A hotter summer is now twice as likely as it was thirty years ago
As meteorological summer begins, Britain stands at a threshold familiar to warming nations: the gap between what infrastructure was built to endure and what the climate now delivers. The Met Office's three-month outlook, released June 1st, forecasts a hotter-than-average season with multiple heatwaves likely — a probability now twice what it was just a generation ago. With reservoirs holding but rivers already falling, and 18,000 homes already losing water during a single May hot spell, the question this summer poses is not merely meteorological but civilisational: how well has a temperate island prepared for a world that is no longer temperate?
- A record-shattering May — 35.1°C at Kew Gardens, the highest ever recorded in Britain for that month — has set an unsettling tone before summer has properly begun.
- The Met Office warns that a hotter-than-average summer is now twice as statistically likely as it was between 1991 and 2020, a shift driven not by chance but by the accumulated weight of climate change.
- Forecasters are divided on rainfall, with MeteoGroup predicting drier conditions across England and Wales while the Met Office leans toward average or wetter outcomes — a disagreement with real consequences for water planning.
- Southern and eastern England entered summer already parched, with some areas receiving only a quarter of expected spring rainfall, and rivers in parts of England already at notably or exceptionally low levels.
- The human cost is already visible: Thames Water recorded over a billion extra litres consumed in a single bank holiday weekend, and 18,000 South East Water customers lost supply entirely during the recent heat.
- Water companies, hospitals, and energy grids are now in a race to prepare for a season that forecasters can characterise but not fully predict — a summer that could be a manageable strain or a genuine crisis depending on whether the rains arrive.
Britain is heading into a summer that could test both its infrastructure and its patience. The Met Office's three-month outlook, released on June 1st — the official start of meteorological summer — forecasts warmer-than-average temperatures across June, July, and August, with an increased likelihood of heatwaves. The forecast follows a late spring that already broke records: a new all-time May high of 35.1°C was recorded at Kew Gardens, surpassing the previous record of 32.8°C set in 1944, and triggering the first heat health alerts of the year.
The climate signal behind the forecast is stark. A hotter summer is now twice as likely as it was during the 1991–2020 reference period — a direct consequence of a warming world. MeteoGroup, which supplies weather data to the BBC, adds that significant bursts of heat are expected to sweep the UK and Europe, with notable temperature spikes possible.
Rainfall tells a more contested story. MeteoGroup anticipates drier conditions across England and Wales in June and July, while the Met Office suggests the season could be average or even wetter than normal. The disagreement matters: although reservoirs are near seasonal averages after a wet winter, southern and eastern England had an exceptionally dry spring, with areas in Essex, Cambridgeshire, Suffolk, and Dorset receiving only a quarter to a third of expected rainfall. Rivers in parts of England are already at notably or exceptionally low levels.
The human cost of heat stress became concrete during the recent hot spell. Thames Water reported over one billion extra litres consumed during a single bank holiday weekend compared to 2025. South East Water saw 18,000 homes lose their supply entirely due to surging demand — households left without water during a heatwave, a situation both uncomfortable and dangerous.
Seasonal forecasts describe averages, not certainties. Cooler spells remain possible even within a warmer-than-average summer. But for water companies, hospitals, and energy suppliers, the message is clear enough: prepare for heat, and prepare for a landscape that in parts of the country is already thirsty. Whether this summer becomes a manageable challenge or a genuine crisis will depend, in the end, on whether the rains come.
Britain is heading into a summer that could test both its infrastructure and its patience. The Met Office released its three-month outlook on June 1st, the official start of meteorological summer, and the picture it painted is one of sustained heat and heightened risk. Warmer-than-average temperatures are expected across June, July, and August, with an increased likelihood of heatwaves and the kind of heat-related impacts that strain hospitals, energy grids, and water systems. The forecast arrives on the heels of a late spring that already broke records—a new all-time May high of 35.1 degrees Celsius was recorded at Kew Gardens in London, shattering the previous record of 32.8 degrees set in 1944. That spike was severe enough to trigger yellow and amber heat health alerts for the first time this year.
What makes this summer forecast particularly significant is the underlying climate signal. According to the Met Office, a hotter summer is now twice as likely as it was during the reference period of 1991 to 2020—a direct consequence of the warming climate. MeteoGroup, which supplies weather data to the BBC, goes further, suggesting that "significant bursts" of heat will sweep across the UK and Europe, with a few notable temperature spikes possible. These are not marginal predictions. They are forecasts built on large-scale weather patterns and the kind of seasonal modeling that governments, energy suppliers, and healthcare systems rely on to prepare.
But heat is only half the story. Rainfall forecasts for the coming months reveal a split among the experts. MeteoGroup predicts a drier period overall, particularly across England and Wales in June and July, with Scotland likely to see closer-to-average precipitation. The Met Office, by contrast, suggests the season could be average or even wetter than normal. This disagreement matters because it shapes what happens next. The UK's reservoirs are currently near or above their seasonal averages thanks to a wet winter, but the picture in the south and east is more precarious. Spring was exceptionally dry across southern and eastern England, with some areas in Essex, Cambridgeshire, Suffolk, and Dorset receiving only a quarter to a third of their expected rainfall. Rivers are already falling to notably or exceptionally low levels in parts of England, and water companies are already flagging stress.
The human cost of heat stress became visible during the recent hot spell. Thames Water reported that over one billion liters of extra water were consumed during the bank holiday weekend compared to the same period in 2025. South East Water went further—18,000 homes lost their water supply entirely due to the surge in demand. These are not abstract figures. They represent households without water during a heatwave, a situation that is both uncomfortable and dangerous. Any sustained heatwave this summer could replicate or worsen these pressures, particularly if the drier forecasts prove accurate and rivers continue their decline.
It is worth noting that seasonal forecasts, for all their sophistication, describe average conditions over three months. They do not predict the specific weather of any given week. Cooler spells are entirely possible even within a warmer-than-average summer. The forecasts are tools for planning, not certainties. They tell water companies, hospitals, and energy suppliers what to prepare for. But they also tell the public something simpler: the summer ahead is likely to be hot, and in parts of the country already stressed by dry springs, that heat will arrive in a landscape already thirsty. How the season actually unfolds—whether the rains come or the drought deepens—will determine whether this forecast becomes a manageable challenge or a genuine crisis.
Notable Quotes
Over one billion litres of extra water were used over the bank holiday weekend compared to the same weekend in 2025— Thames Water
The Hearth Conversation Another angle on the story
Why does a summer forecast matter so much? Isn't it just weather?
Because when you're running a water company or a hospital, you need to know what's coming. If you know heat is likely, you staff up, you prepare. If you don't prepare and it arrives, people lose water or wait in emergency rooms.
But the forecasters disagree on rain. How do you plan around that?
You plan for both scenarios. You assume drier conditions in the south and east because that's where the stress already is. You hope for the wet scenario. But you don't bet on hope.
The 18,000 homes without water—was that because of the forecast, or because it actually happened?
It actually happened, last week. That's the real warning. The forecast is saying: this could happen again, for months.
Is this climate change, or just a bad year?
Both. Bad years are becoming the pattern. A hotter summer is twice as likely now as it was thirty years ago. That's not chance anymore. That's the new normal.
So what should people actually do?
Pay attention to water use. Don't assume the taps will always work. And understand that heat in a dry landscape is different from heat in a wet one. One is uncomfortable. The other is dangerous.