How hot is too hot to run?

Today is the first day in 5 days since I ran outside. It’s just been too hot.

I usually run at 8pm when the sun is covered behind the trees but still light enough for me to sneak a run before it gets too dark. I usually consider 80 degrees Farenheit too hot on a normal day time, but 80 degrees at dusk is cool enough for me.

The past several days reached upwards of 85, 86 degrees at 8pm. Now that is too hot for me. It’s too humid. I can’t breathe through all the moisture in the air. I don’t want to get angry at the heat (I can get hangry that way). But with that came a pretty long series of rest days where I didn’t run. My muscles definitely felt like waking up from a nap during today’s run.

I think the hottest I will run (with no direct sunlight at me) is probably 81 or 82 degrees. I wonder what other runners’ thresholds are. How do they keep their muscles awake and working when the outdoor conditions are not great. I just wonder.