Runners warned against wearing fancy dress as temperatures set to soar for London Marathon

Runners have been warned to rethink wearing fancy dress and run at a slower pace for the London Marathon on Sunday as temperatures are set to soar.

Warm and sunny skies are forecast and runners tackling the 26.2 mile course can expect temperatures to reach highs of 22C degrees.

Although sunshine and warm weather may sound favourable, Professor Sanjay Sharma, medical doctor of the TSC London Marathon warned runners that the heat could be a health risk.

“In the conditions forecast for Sunday, you should slow your planned pace. If you were planning to run in fancy dress, please think carefully whether that is still appropriate in the conditions,” he said.

Instead, he suggested runners wear “appropriate clothing” that is lightweight and designed for warmer conditions.

“A thin cap will keep the sun off your face, which will further reduce the effects of the heat,” he added.

Professor Sharma also suggested runners wear waterproof sunscreen because they will be out in the sun for several hours.

Some 56,000 runners are expected to descend on London for the 45th edition of the race this weekend, which could be the world's largest marathon if the number of finishers exceeds the 55,646 who completed the New York Marathon last November.

However, temperatures earlier in the day are set to be cooler and more comfortable for runners and are not expected to peak until 4pm.

Met Office spokesman Oli Claydon confirmed the favourable outlook, stating, "It’s looking like the marathons for both Manchester and London will be dry."

He added: “Temperatures shouldn’t be a problem for the morning, but the temperature will build during the day.”

The sunny spells will be followed by a mini heatwave in the coming days with temperatures predicted to hit 26C degrees on Wednesday, according to the Met Office.