London Marathon organizers issue heat alert for Sunday's race — here’s how 3 elite runners plan to stay cool (2025)

With temperatures expected to hit 68°F/20°C, the organizers of the TCS London Marathon have issued a weather warning to all participants ahead of this Sunday’s race.

In an email sent on April 24, runners were urged to adapt their goals, hydrate properly, and dress for the heat.

If you're racing on Sunday or in the midst of training for a different event, knowing how to prepare for the weather is crucial.

I spoke to three elite athletes who’ve been there: British marathoner Jonny Mellor, GB triathlete Alex Yee, and Swiss wheelchair racer Catherine Debrunner. They shared their personal tips for staying cool and running strong in the sun.

What the organizers said about Sunday’s heat

The official forecast for race day is currently 68°F/20°C, which is considered warm for marathon conditions, especially if you're not accustomed to running in the heat.

In an email to participants, the TCS London Marathon team, alongside Medical Director Professor Sanjay Sharma, advised runners to:

• Adjust your pace: Slow down to match the conditions, and reconsider any fancy dress plans if it’s too warm.
• Listen to your body: Stay hydrated, slow down if tired, and visit the First Aid Stations if you feel unwell.
• Wear the right gear: Choose lightweight, moisture-wicking clothing and consider wearing one of the best running hats for sun protection.
• Hydrate wisely: Drink to thirst at stations which will be provided regularly from Mile 3 to Mile 24, but avoid overdrinking.
• Cool down at showers: Use the 18 Shower Stations along the route to stay cool.
• Prevent chafing: Apply petroleum jelly or tape to sensitive areas.
• Apply sunscreen: Protect exposed areas of your body with waterproof sunscreen before the race.

Advice from the pros

Last night, I attended the New Balance Townhouse launch event last night — a community hub created to support runners ahead of the 2024 TCS London Marathon — where I spoke to three elite athletes about racing in the heat. Here’s the expert advice they shared.

Alex Yee, Olympic gold and silver medallist in triathlon for Team GB

“I think taking on nutrition and missing water stations is quite easy to do,” Yee shared.

“So I would say just don't make that compromise on yourself. Make that commitment early doors to take those early water stations. Make sure you take that golden opportunity as early as possible because it's an investment for later on in the race.”

Catherine Debrunner, Swiss Paralympic champion and world-record-holding wheelchair racer

"I agree that hydrating is even more important and I always need to remind myself to actually drink,” she said. “We have the Camelbak ($60, Amazon), and it's a little bit tricky to drink. So it takes some seconds. But in London, there are actually good parts where you can have a drink.”

She added that temperature affects wheelchair athletes differently due to the shorter race time. “For us, I think the heat is less issue than for the others, since we are done in about one hour and forty-ish. So I don't think it's going to be that warm."

Though as a fan of the heat, she added: “I personally like it a little bit warmer. So I’m pretty happy with the forecast.”

Jonny Mellor, British marathoner and coach with a personal best of 2:10:05

“It's about making sure you stay well hydrated in the days leading up to the marathon,” he said.

“Keep cool beforehand, some people will use an ice vest, you can even just pour cold water over your head at the start line.”

Mellor also recommended warming up in the shade if possible, and adjusting your expectations for pace: “If you think it is going to be warm, don't be afraid to kind of just slow down where you are and make sure you can get to that finish line as well.”

At the water stations, he suggested a dual approach: “Have some drink but also, as I say, tip some over the top of your head as well, just cool yourself down as much as possible.”

You've trained hard to get to this point, now it's about pacing yourself, staying hydrated, and keeping cool. Listen to your body, adjust your goals for the heat, and don't be afraid to slow down if needed.

However your race unfolds, getting to the finish line safely is the win.

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