Live forecasts update automatically; written guidance last reviewed 20 June 2026 by the Current UK weather desk. Data from national met services via Open-Meteo.
A heat wave is a prolonged period of unusually hot weather, often with high humidity. In the UK, it’s officially declared when a location records at least three consecutive days with maximum temperatures reaching a specific threshold, typically 25–28°C depending on the region.
When do UK heat waves usually happen?
Heat waves most often occur between June and August, though the hottest spells can stretch into early September. July is statistically the peak month, especially in southern England and the Midlands. The 2022 record of 40.3°C at Coningsby (Lincolnshire) showed that extreme heat can now arrive earlier in summer.
How to stay comfortable and safe during a UK heat wave
If you’re travelling or working outdoors, plan for early mornings or evenings when temperatures are lower. Light cotton clothes, a wide-brimmed hat, and reusable water bottles are essential. In cities like London, Birmingham or Bristol, the urban heat island effect can push night-time temperatures up noticeably, making it harder to cool down. Check the 10 day weather forecast UK to time your trips.
Frequently asked questions about heat waves
What is the Met Office definition of a heat wave?
It uses the heat wave temperature threshold specific to each UK county. For most English counties the threshold is 27–28°C, while in Scotland and Northern Ireland it is lower (around 25°C).
Can a heat wave affect driving or public transport?
Yes. Tracks can buckle, overhead wires sag, and road surfaces may soften. National Rail often introduces speed restrictions in extreme heat. Check travel updates and carry extra water if you’re on the move.
Are heat waves becoming more common in the UK?
Climate projections show that by 2050 a 40°C day could happen roughly every three to four years. The heat wave movie of recent summers is consistent with warming trends; it’s no longer a rare event for southern Britain.
For local conditions, see our Liverpool Weather and Glasgow Weather pages. If you’re heading south, Bristol Weather is also worth checking.