10/06/2026
HELP! My race forecast is unseasonably warm. š
If youāve been refreshing your weather app every 20 minutes, this oneās for you. The number one question in my DMs this fall: Do I still go for my goal?ā
The answer is not surprising, heat costs you time. Not because youāre soft or your training failed, but because your body is doing two jobs at once. Job one is holding race pace. Job two is dumping heat, which means sending more blood to your skin and sweating buckets. Your heart can only share so much between those jobs, so something gives. That something is pace.
How much? The research (mostly marathon data) gives us a starting point:
ā”ļø 5:45/mi or faster: roughly 1 sec/mile slower for every 1°C (1.8°F) above about 59°F
ā”ļø 7:25-10:00/mi: roughly 4-4.5 sec/mile slower per degree
Part of that gap is time on course. Out there for 4+ hours? The race literally heats up around you.
Then thereās humidity. Look at DEW POINT, not relative humidity. The more moisture in the air, the less your sweat can evaporate and actually cool you. Coach Mark Hadleyās āheat scoreā (temp + dew point) is one of my favorite quick tools, and the full chart is in the slides in °F and °C.
Takeaways:
1ļøā£ Adjust your goal BEFORE the gun. Deciding at mile 18 that itās too hot is not a strategy.
2ļøā£ Donāt ābank timeā while itās cool. That debt comes due with interest.
3ļøā£ Pace by effort, not just your watch.
4ļøā£ Bump up fluids AND electrolytes, but donāt overdo the plain water.
5ļøā£ Confusion or acting āoffā in the heat is an emergency, even if the runner is still sweating.
A hot race isnāt a failed race. Some of the smartest races Iāve seen came on days when runners adjusted early and passed a LOT of people in the last 10K.
Save this for race week and send it to the friend already panicking about the forecast. Racing somewhere warm? Drop your race and forecast below and how you are feeling about it.