Runners have been given advice ahead of this weekend's London Marathon - as temperatures are set to soar.

Event organisers tweeted a list of advice for runners.

The Met Office says Saturday will start dry and sunny, with thundery showers rolling in over the afternoon.

Temperatures will remain at roughly the same as Friday in the south of the UK.

With the London Marathon on Sunday, runners and spectators will be keeping a close eye on the weather. Temperatures are likely to still be high and after a humid start, temperatures are likely to reach 22 °C with a chance of 23 °C, although trackside measurements may exceed these values. According to Met Office records, the warmest London marathon on record was in 1996 when it reached 22.7 °C in St James’s Park. Elsewhere temperatures will have started to decline slightly with high teens in large parts of England and Wales and mid-teens in Northern Ireland and Scotland.   

Met Office Chief Meteorologist Will Lang said: “Many people will be happy to hear that the warm conditions are forecast to stay around for the weekend, although there will be some heavy thundery showers to watch out for at times. If you are out enjoying the weather remember to protect yourself from the sun, which is now at full strength.

“For those running the marathon, make sure you stay up-to-date with the forecast as there will be high temperatures and humidity to contend with. Stay hydrated and listen to advice from the event organisers.”

Advice from Runner’s World to those running the marathon is to be mindful of the impact the warm weather can have on them. Every 2-3 °C rise in temperature above 15°C can slow a runner's pace by as much as 20 to 30 seconds per mile. It is worth considering starting slower than you may have planned. And to make getting to the finish running strongly the main goal, and to run by perceived effort rather than mile splits.