Guides

Three numbers, three different formulas, three different jobs. Here is when each one matters and which one your weather app is probably showing.

ACSM and OSHA both publish hourly fluid intake recommendations indexed to heat. Here is the table, what it means in cups, and where most people get it wrong.

Both look similar to a bystander, but heat stroke kills in under an hour without cooling. The single symptom that distinguishes them, and what to do for each.

It is not about the air being hotter. It is about your sweat not being able to do its job. Here is the actual mechanism.

Your body builds heat tolerance in about two weeks of progressive exposure. Here is the protocol used by the military, OSHA, and college football programs.

The NWS uses four named risk bands for heat index. Here is exactly what each one means, when it is issued, and what actions are recommended.

Car thermometers, asphalt, and shadeless concrete patios are not measuring the same thing the weather service measures. Here is what each is actually telling you.