From the Exhaustion rules: "Some special abilities and environmental hazards, such as starvation and the long-term effects of freezing or scorching temperatures, can lead to a special condition called exhaustion."

educated guess says that exhaustion terrain effects are found in individual adventures as specific hazards; for cold, I would possibly check adventures like Icewind Dale: Rime of the Ice Maiden, maybe Storm King's Thunder, anything that specifically ventures into cold regions to see if those places have exhaustion hazards.

oooh, also see the rules for extreme hot/cold hazards in the DMG, forgot about those

5e is OK

@MissMisinformation How does exhaustion from extreme hot/cold work if you are resting (which is the way you get rid of exhaustion, if I'm not mistaken)?

there's not a specific rule that I can find reasonably quickly specifically in that venn diagram overlap of "in extreme cold" + "resting", but if nobody has the ability to take sensible precautions currently (or were underprepared and the precautions they are taking don't cut it), I can see a situation where you have to keep making saving throws against extreme climate even during the rest, resulting in a net worse condition

Thanks. Sounds like the answer is more complicated than I thought (was expecting it to be obvious), so I might ask this on the main site

This is a cool video:

It's probably something lots of people are already doing, but it's about focusing on player goals

@Allure not a bad idea tbh. you'll probably get a more comprehensive answer (or at least a more coherent/better formatted one, sorry!)