A soldier collapsed on the Mall in London on Monday due to high temperatures reaching towards 30C during a rehearsal for a state visit by the Emperor and Empress of Japan. The cavalry guard was helped to their feet by a fellow guard. The procession is scheduled for Tuesday and is hosted by King Charles.

The incident occurred amidst a heatwave in London, with temperatures predicted to reach 27C on Monday and possibly hitting 30C by the end of the week. The UK Health Security Agency and Met Office have issued a yellow heat health alert for most of England, excluding the North-East, warning of potential health impacts and increased indoor temperatures for vulnerable individuals.

Liam Eslick from the Met Office noted that UV levels would be high, and people should take precautions against the intense sun. The mini-heatwave marks a shift from a rainy spring, with most areas expected to experience a slight temperature cooldown and possible thundershowers by late Wednesday into Thursday.

An official UK heatwave is identified when temperatures meet or exceed specified thresholds for three consecutive days. In London, this threshold is 28C.