it did go over 30° the last time i was there. but tbf also that’s the hottest it gets

40C in London in 2022,

https://www.londonworld.com/news/weather/heatwave-london-weather-highest-ever-temperature-recorded-uk-heathrow-airport-3773879

37.7C last month (June 2026)

https://www.metoffice.gov.uk/blog/2026/june-2026-heatwave-a-recap-of-the-temperature-records (for avoidance of confusion those are the records for June - the 40C was July 2022)

Anything over 28C is currently classified as a heatwave, but I think they're going to have to revisit that, or just say "all summer is a heatwave try not to die" given 32-35C has been consistently hit pretty much every summer this decade.