Parts of the UK experienced the warmest April day in almost 70 years with temperatures in central London reaching 28C (82F), prompting warnings for competitors in the marathon.
On Thursday the balmy spell peaked in England’s south-east, where it was hotter than Spain and Italy. Temperatures reached 28.3C in St James’s Park, central London, and 27.9C in Northolt, north-west London.
The temperatures made the day the warmest of the year so far and the hottest April day since 1949 when the mercury soared to 29.4C.
Sunday was not expected to be as hot, however forecasts of 23C in the capital would mean the London marathon becoming the warmest of those races on record. Conditions could be especially difficult for runners in fancy dress on the 26.2-mile route, organisers said.
The event director, Hugh Brasher, said: “The previous highest temperature on race day was 22.2C in 1996 and 2007. We will continue to monitor the forecast closely as we all know that weather forecasts can change.
“Our contingency plans for the forecast hot weather on Sunday include increasing the supply of water to all drinks stations to enable runners to douse themselves with water, increasing the number of showers on the route and increasing the supply of ice to first aid stations on the route.
“Most importantly, runners should adjust their goal for Sunday and plan to run at a slower pace. If they were planning to run in fancy dress, they should think carefully if that is appropriate in the forecast conditions.”
The heatwave has come more than a month after the UK struggled with snow and ice from the “beast from the east”.
Now summer has come unusually early: the hot spell far exceeds the average maximum temperature for April of 11.4C.
The summery weather is caused by warm air from the Azores being dragged towards the UK due to an area of low pressure over the Atlantic and high pressure over western Europe.
Thursday is expected to be the hottest day of the warm spell, with weekend temperatures dipping slightly before showery outbreaks on Sunday.