The Bradford runner was fourth in the Olympics last summer and was in medal contention again after forging part of a 15-man pack at the front.
However, the energy-sapping morning heat – 26 degrees and 83% humidity at 9am – wore him down and he started to drop back from the leaders and eventually stopped.
“Obviously I’m disappointed but I tried my best and that’s all you can do with it,” the 27-year-old said.
“I feel like I just got too hot, simple as that really.
“I tried at all the stations to be diligent with the ice and the sponges. It helped but I still got too hot. It was fairly sudden to be fair.
“I felt pretty good the first 25k, and then 30k I was still feeling good.
“Then about 32k maybe I just really suddenly didn’t feel good anymore. Obviously we started going a bit faster so that was probably it.
“It’s just really hot. When I stopped I just took ages to just feel alright again.”
Emile Cairess was a DNF around the 35km mark in the marathon, after sticking with the leading pack for most of the race.#WCHTokyo25 #NovunaGBNI pic.twitter.com/Ur7MvRYaAU
— British Athletics (@BritAthletics) September 15, 2025
Japan’s high humidity has been a main talking point in the first few days of these Championships.
World Athletics opted against moving the marathon and race walking events to Sapporo – 700 miles north – as the Olympics did when they were staged here four years ago due to the sweltering summer heat.
These Championships were nudged back to mid-September from their usual August date for multiple reasons, one of which was Japan’s usually cooler autumns.
However, this has been Japan’s hottest ever summer, with average temperatures between June and August 2.36 degrees up on the norm, and the hot weather has continued into this month.
Cairess said he did his best to prepare but it was not enough.
“I did a decent amount,” the Leeds City runner said.
“I did loads and loads and loads and I felt like I did as much as I could while I balanced with training. I’ve only done four marathons.
“Paris was obviously hot but not like this. Paris was warm I’d say. Whereas this was very humid. I have not known conditions like it.”
The marathon was won by Tanzania’s Alphonce Felix Simbu, who outsprinted Germany’s Amanol Petros in the closing stages to finish just 0.03 ahead.
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