CapnZapp
Legend
Somebody just argued temperatures rarely get that high in the rainforest... *shrug*100 F is not a high threshold. We just had an entire week above 100 (and an entire month straight of above 90, with index about 100), and it's supposed to be over 100 this next week here in Oregon. OREGON! In September! Arizona is always above 100 from late spring to early fall pretty much every day. Arizona, Nevada, California, etc all have reached over 100 just today. Jungles, in September as of right now, are in the upper 80s and 90s, and with humidity, the heat index is well over 100.
So no, it's not a high threshold. It's pretty much guaranteed in deserts and jungles during the warm seasons.
I'd think many groups just create food and water, or make a Survival check or something, and then ignore the rule.Also, did you read the part where you need 3 gallons a day? That's a lot of water. 24 pounds of water per person per day.
So again, no. This won't happen only "where the DM wants heat exhaustion to be a thing." It should happen any time the DM follows the already existing rules when the PCs are in an area that reaches those temperatures during the summer. Which, as I noted, is not just desert or jungle. They'd be applicable for pretty much the whole summer even here in the pacific northwest.
I'd rather there be a blanket rule "wear heavy armor, get this penalty" than having to bother tracking supplies myself.