Londoners have been asked not to leave their engines idling or burn garden waste as a high air pollution alert comes into effect in the capital.
City Hall gave the warning on Tuesday as temperatures in part of the city could reach 34C.
Parts of west London will see some of the hottest weather in the country, with
The area saw the highest temperature in the UK on Monday with 31.9C.
The London Ambulance Service has warned that it is expecting a very busy period for the emergency services due to the heat.
The LAS asked Londoners to take extra care and to check on elderly relatives and neighbours.
More very hot weather and a @UKHSA heat warning in London this week. Take extra steps to stay well:
— London Ambulance Service (@Ldn_Ambulance) August 11, 2025
💧 Stay hydrated
🧴 Wear sunscreen
⛱️ Find shade
💊 Carry your medication / inhaler
💚 Check on elderly relatives / neighbours
Use 111 if you need urgent medical advice. pic.twitter.com/RNZaU25cof
Meanwhile, National Rail warned that the hot weather may cause trains to be disrupted, explaining that heat can cause overhead lines to expand and sag, create line-side fires and cause rails to buckle.
The sweltering conditions are expected to create ‘High’ ozone levels as the strong and prolonged heat and sunshine reacts with any pollution in the air.
Imperial College London forecasters advised City Hall to issue an alert, with air flow from mainland Europe expected to increase ozone levels.
High air pollution alerts will be displayed at public locations across London, including all bus stop countdown signs, as well as on the Underground.
The Deputy Mayor for Environment and Energy, Mete Coban said: “London’s toxic air is responsible for around 4,000 premature deaths in the capital each year, which is why the Mayor has done everything in his power to tackle it, including launching the world’s largest clean air zone.
“We are urging Londoners to look after themselves in this pollution alert during the hot weather, stop their engines idling, and refrain from burning wood or garden waste – all of which contribute to high levels of pollution.
“This is particularly important in order to protect those who are most vulnerable as we continue working to build a safer and greener London for all.”
This varies across the country and in London, the temperature is 28C.
Experts warn climate change is driving more extreme weather conditions in the UK, worsening drought and dry spells, and making heatwaves more frequent and severe.
Despite unsettled weather in July with many places seeing heavy rain or showers, it was still the fifth warmest on record.
