Does anybody else get thirsty after a hot shower? I very frequently do.
Just now took a 33oz Poland spring bottle and finished it in one shot. That's a record for me. Usually it's those smaller ones screw cap ones or sports bottle ones
We sweat in a hot shower just like in a hot room, but we don't notice the sweat because it's rinsed right off. When our body loses water, it's normal to feel thirsty and to drink, in order to replace the lost water. Perhaps yesterday you started out more dehydrated than usual, due to sweating more in the heat, or having a saltier than usual supper, or taking a longer or hotter shower than usual.
If you have a very accurate scale, you might be able to measure this water loss. Weigh yourself right before stepping into the shower, then again right after coming out and drying off. (Obviously, there's another way to lose water in the shower besides sweating, but at least for purposes of this experiment, try to avoid that.)
If you typically drink a 17 ounce bottle of water afterwards, then you'll probably find that you lose about 17 ounces, or about one pound while showering. Last night, you might have lost as much as 2 pounds.
Some people used to think that they could go to a shvitz to "sweat out the pounds". Unfortunately, the weight lost by sweating is just water, and you gain that weight back as soon as you drink water or eat food containing water, which is basically every food. Even matzo is 4% water.
It makes sense to drink the water that you feel you need to quench your thirst, although there's some salt is lost in sweat as well, so if you're sweating a lot, you might want to drink something like Gatorade which replaces both water and salt.
If you find it bothersome, make the water less hot, take shorter showers, keep the window open or exhaust fan on so heat doesn't build up in the room, and at the end of the shower don't turn off the water suddenly, but gradually turn off the hot water so the cooler water helps your body cool down before you get out.