Back in the 80s a few military organizations went to a [censored]/drink on demand standard in the field during hot weather. August in Camp Blanding, pushing 100F, no wind, 100% humidity can eat your lunch.

At the first sign of dragging, other times entirely randomly, someone would tell you to take a leak. If you couldn't produce a good stream you were told to drink a canteen full of water. Other times they would just tell you to drink, just making sure.

Mostly it was the macho guys who were too tough to drink, and a few country boys who think 'you sweat less if you don't drink', as if that was a good thing, that had issues. They were usually the ones who got 'bear caught' and fell out. It can come up fast. One minute I was talking to a guy who looked a bit winded and the next he was on the ground having convulsions. Serious enough a situation that we flew him out by helicopter packed in ice.

We had had problems but after that it was [censored]/drink on demand.

Cold weather doesn't drop the bodies from dehydration as quickly. It kind of sneaks up on people. Cold seems to suppress the feelings of thirst. Under such conditions dehydration can make you feel colder, make you more prone to frostbite and generally decrease physical and mental performance. Having a few people who had to be surgically 'opened up' with a glorified apple corer due to 'fecal impaction' caused by dehydration, described as the worse case of constipation imaginable, caused a greater emphasis to be placed on proper hydration.

Good times.