Temperatures in the UK surged past 29°C on Wednesday, marking the start of what forecasters predict will be the country’s first official heatwave of 2025. The Met Office defines a heatwave as a period of at least three consecutive days where daily maximum temperatures meet or exceed region-specific thresholds, ranging from 25°C in Scotland and Northern Ireland to 28°C in parts of eastern and southeastern England. With highs forecast to reach over 30°C in several areas, and some predictions suggesting peaks of 33°C or even 34°C later in the week, many regions are expected to meet these criteria for the first time this year.

A strong high-pressure system is currently stationed over southern England, drawing warm, humid air from continental Europe and creating widespread sunny, dry conditions. This weather pattern is responsible for the rapid escalation in temperatures, with the warmth expected to persist through the weekend. Major cities including London, Birmingham, and Manchester are likely to see temperatures well above the June average, which typically hovers around 18°C, making this spell notably intense for the time of year.

The UK Health Security Agency has responded by issuing a yellow-level heat health alert for large parts of England, including London, effective through Sunday. These alerts, developed in collaboration with the Met Office, serve as early warnings for health and social care professionals, focusing on the increased risks for vulnerable populations such as the elderly and those with pre-existing conditions. Overnight temperatures are also being closely monitored, as they play a critical role in how well people cope with sustained heat.

Recent research by the Met Office underscores that such extreme heat events are becoming more common due to climate change, with the likelihood of UK temperatures exceeding 40°C now over 20 times higher than in the 1960s. The study warns that longer, hotter heatwaves are expected in the future, highlighting the urgent need for adaptation and preparedness as the nation faces increasingly frequent and severe hot spells.