London is now under a UK Health Security Agency (UKHSA) Yellow Heat Health Alert, active from 12 pm today, Saturday, July 4, until 5 pm on Wednesday, July 8. Temperatures are set to climb significantly, with forecasts predicting up to 12 consecutive days above 28°C.
The Met Office expects London to reach around 32°C on Monday, July 6. By Thursday, July 9, temperatures could soar to 39°C across London and the South East. This follows a record-breaking June 2026, which saw 37.7°C in Lingwood, Norfolk, and 36.4°C at Heathrow, prompting the first-ever Met Office Red Extreme Heat warnings.
Met Office Chief Meteorologist, Andy Page, previously stated that such exceptional heat requires the public to 'adapt their daily routines'. The Met Office officially defines a heatwave in London when daily maximum temperatures reach or exceed 28°C for at least three consecutive days.
What to do immediately
Protect yourself and vulnerable individuals during this prolonged period of high temperatures. Take these steps:
- Stay Hydrated: Drink plenty of water, even if you don't feel thirsty. Avoid excessive alcohol.
- Seek Shade: Stay out of the sun between 11 am and 3 pm, the hottest parts of the day.
- Cool Your Home: Keep windows and curtains closed during the day to block heat. Open them at night when it's cooler.
- Check on Others: Look in on elderly relatives, neighbours, or anyone who may be vulnerable to the heat.
- Dress Appropriately: Wear light, loose-fitting clothing and a wide-brimmed hat if outdoors.
- Avoid Strenuous Activity: Limit physical exertion during peak heat hours.
But there are risks
While the Environment Agency reports a 'very low' flood risk across England for the next five days with no current flood alerts, historical patterns show that intense heatwaves can be followed by heavy rain and thunderstorms, leading to flash flooding. This type of surface water flooding is not covered by Environment Agency warnings.
UK waters, particularly the English Channel, are also experiencing a marine heatwave. Conditions are expected to escalate next week, with a risk of reaching 'extreme' levels, a classification rarely seen in UK waters.
What this means for you
You should adjust your daily schedule to avoid the hottest parts of the day and take proactive steps to stay cool and hydrated. Be aware of the signs of heat exhaustion and heatstroke in yourself and others.
What happens next
The UKHSA Yellow Heat Health Alert remains in place until Wednesday, July 8. High temperatures are forecast to continue for up to 12 days, with the Met Office predicting temperatures to reach 39°C by Thursday, July 9. Monitor Met Office and UKHSA updates for any changes to warnings or advice.
Sources
- Met Office — London heatwave definition and temperature forecasts (July 2026)
- Met Office — June 2026 record temperature data and Red Extreme Heat warnings
- UK Health Security Agency (UKHSA) — Yellow Heat Health Alert for London (July 2026)
- Environment Agency — Flood risk assessment (July 2026)
- BBC Weather — London heatwave duration forecast (July 2026)
- Met Office Chief Meteorologist, Andy Page — Statement on June 2026 heatwave