Londoners will see the hottest day of the week on Monday, August 3, when the BBC forecast predicts a high of 33C, but that heat will not carry over into a full heatwave. Instead, temperatures are expected to settle between 23C and 28C from Tuesday, August 4, through Sunday, August 16.
Despite the warm conditions, forecasters say the capital will dodge the official heatwave threshold. The Met Office defines a heatwave as a period of at least three consecutive days with daily maximum temperatures meeting or exceeding a specific level – for London, that level is 28C. The BBC’s day-by-day forecast, which runs to August 9, shows no three-day stretch at 28C or above in that window.
Why 28C is not always a heatwave
The Met Office is careful with the term. A single hot day, even one reaching 33C, does not automatically constitute a heatwave. For London, the temperature must hit at least 28C for three or more days in a row. The BBC’s extended forecast to August 16 shows 28C on August 12, 13, and 16, but those days are not consecutive, meaning the official definition is not met.
Met Office guidance explains that heatwave thresholds vary across the UK, reflecting regional differences in typical summer temperatures. In London, the threshold is set at 28C because the capital generally experiences warmer conditions than northern or western parts of the country.
What the Met Office says about the heat
While the Met Office’s detailed daily forecast only extends to August 9, its long-range outlook indicates that above-average temperatures are likely to persist, especially in southern England. In a statement, the forecaster said: “For the most part, temperatures look to remain above average, especially in the south, though perhaps without the exceptional heat we have seen in recent weeks.”
This suggests London will stay warmer than usual for early August, but the extreme heat that has scorched the capital’s parks and gardens in recent weeks is unlikely to return during this spell. Scorched grass has become a familiar sight around London, and while the coming days will be warm and mostly sunny, the intense, prolonged heat from earlier in the summer is not on the horizon.
London's day-by-day forecast
Here is the full forecast for the capital from August 3 to August 16, according to the BBC:
- Monday, August 3: High 33C, low 18C, sunny with a gentle breeze
- Tuesday, August 4: High 27C, low 17C, sunny intervals and a moderate breeze
- Wednesday, August 5: High 25C, low 13C, sunny intervals and a moderate breeze
- Thursday, August 6: High 23C, low 13C, sunny intervals and a gentle breeze
- Friday, August 7: High 24C, low 14C, sunny intervals and light winds
- Saturday, August 8: High 24C, low 14C, sunny intervals and a gentle breeze
- Sunday, August 9: High 25C, low 15C, sunny intervals and light winds
- Monday, August 10: High 26C, low 15C, sunny intervals and light winds
- Tuesday, August 11: High 27C, low 15C, sunny with light winds
- Wednesday, August 12: High 28C, low 15C, sunny with light winds
- Thursday, August 13: High 28C, low 16C, sunny intervals and light winds
- Friday, August 14: High 27C, low 16C, sunny with light winds
- Saturday, August 15: High 27C, low 15C, sunny with a gentle breeze
- Sunday, August 16: High 28C, low 15C, sunny with a gentle breeze
What this means for London
The warm weather will give many Londoners plenty of opportunity to enjoy outdoor plans, but it will not come with the health warnings or extreme heat alerts that often accompany a genuine heatwave. The Met Office’s long-range forecast indicates that temperatures will remain above average, but the exceptional peaks seen in recent weeks are not predicted to return.
For those hoping for a break from the heat, the upcoming period offers a slight dip from Monday’s 33C, with most days settling in the mid-to-high 20s. Evenings will be relatively mild, with lows ranging from 13C to 18C, providing some relief after sunny days.
While the term “heatwave” might be technically absent from the forecast, the capital is still set for a long stretch of warm, settled weather. As the Met Office put it, the heat will remain above average – just without the exceptional intensity that has marked recent weeks.
