How hot is too hot to run?

No sweat, I run on a treadmill in a sauna. Set to 100 degrees. Celsius.

It all depends what you're used to. In Arizona at the high school state meet many years ago, during the 1600 m, it was 108 F. I also ran the day we hit 122 F.

Isn't 🐬Florida🐬 hot and humid?

Above 30°C is usualy considered not healthy any more.

Uh, what? This isn't true, and while normally I wouldn't care, this could actually get someone hurt. It certainly can be hot and humid. Look at dew points if you want to compare different locations. A refresher: Dew point is the temperature where relative humidity is 100% - the air can't hold any more water w/o supersaturation.

These are the average dew points for all of last August (using Weather Underground, since you posted it):

Riyadh: 47F

Phoenix: 64F

Houston: 73F

Miami: 74.5F

So... using a handy dandy humidity calculator from the Googles, Riyadhi at 90F in August... that's 22.8% humidity. in Miami? 60.5% One of these is not like the other.

Wrong, and don't cloak your cope with a self-righteous protector cape. Did I not say stay near water? Did I not warn that sweat has its limits, and to go slow enough to not overheat? That it's a better idea to go swimming?

"dew point, dew point" blah blah. Save that shell game for the uneducated. OP is talking about temps in the mid-90's, remember? Which can hold far more water than 70s or 80s. Once it gets that hot, you have to be somewhere pretty special for it to be humid at the same time.

What happens when heating air does absorb a lot of water? It clouds up, blocks out the sunlight and temps max out in the 80s. That's what happens in your "hot n humid" Florida-type spots. Go see for yourself the max temperature predicted in Miami for the next week - 85F. Warm, but certainly not hot, let alone dangerously so.

You can have warm and humid, if you need to save face.

If the temperature (in Fahrenheit) and humidity combined is over 150 I run shorter and slower. Of course it is rarely over 95 Fahrenheit here. can't comment on places with 10% humidity and high temperatures although I did visit Las Vegas for a week once and the 90 degree heat didn't bother me at all.

This is flat out disinformation. In the U.S. near the east coast or Great Lakes it can get to 90 degrees with 70% humidity for days on end in the summer. How hot too hot is for running depends on the type of run, humidity, and whether it's sunny. For me living 2 hours from the east coast around 95 degrees is my limit but I prefer 90 or below for easy runs and 80 or below for workouts and long runs to make sure I can get the mileage in without any problems.

Don't bother reading dumb wigans' diarrhea filled posts.

If you are interested in a useful measure of when the combination of temperature and humidity is dangerous, read about 'wet bulb' temperatures.

Just stop with the "I'm the public health department" crap, people. You're not protecting anyone. I'm not telling anyone to go run too fast in any temperature.

What I AM doing is explaining, and you'd do well to swallow your pride and pay attention, that peak temperature on hot days is generally not humid. These don't peak at the same time of day.

Once you get over your self-righteous indignation, start thinking about what happens when you have to sweat to stay cool in those 90s temps OP is asking about. If there anything dangerous being peddled here, it's the idea that those temperatures are humid, rather than dangerously dry. Humidity impairs the ability to sweat, drenching your skin. But when it's hot, you typically sweat all too well, even if your skin looks like it's staying dry. Those who don't understand this (such as possibly OP) risk dehydrating very quickly.

Get over your bent feelings and think about it. Don't snap back, just think about it.

To help you along, here's the original main point: if it's 85F, that's 13 degrees below body temperature. Heat naturally escapes your body on its own.

when it's 98, that's body temperature. Heat leaves only one way: the change in state from liquid to gas of the sweat on your skin.

I just saw one of his posts on another thread - and geez, you are right. Noted.

Yes, Riyadh is mostly hot and dry.

That does not mean the entire Arabian Peninsula is as well.

Take a look into cities on the ocean like Dubai, Doha and Muscat.

Humidity can be 80-100% with +30 deg C temperatures.

Trust this: it is hot and humid over here.

I am definitely not designed well to run in the heat. I'm half Nordic/half Mexican, and I clearly was built for colder weather (living in Portland definitely helps vs. the So Cal desert I grew up in). I don't sweat a lot, my core temp spikes quickly, and I'm pretty much useless over 90 degrees if forced to work outdoors. I get light-headed, bright green light in my eyes and soon after, I'm likely to faint, regardless of how much hydration I have. My worst races came when we got October/April-May heat spikes, and almost all of my PRs came in 70 degree weather or less. Everyone is different - I'd say for people acclimated to heat, you can run into the 100s without too many repercussions if you hydrate and listen to your body (muscle cramps are a potentially early sign of heat exhaustion/stroke).

I should have near the shiittest genes in the world for coping with heat yet for some reason I love it.

Come to Northern Europe, its 60-70 degrees Fahrenheit here and that's a heatwave.

Apparently Syd and Mu are both too hot to run.

I've run in central TX and the se coast around Savannah GA. It will get 90-100+ with dew points in the 70s.

I've run in the middle of the day in these places. You just drink water and endure. If you are acclimated it is fine.

I have also run in -30 windchill and a 3mi run in 2ft of snow.

Alan