I needed rules for cold climates for 5e, and the DMG isn’t out yet. Voila!
Severity of Cold Environments:
40 to 0 degrees
Every ten minutes, DC 5 Constitution-Survival check, or suffer a level of exhaustion.
- Severe Cold
-20 to 0 degrees
- Extreme Cold
-50 to -20 degrees
- Supernatural Cold
under -50 degrees
note: Wind chill may change the effective temperature, so lack of shelter from the wind may dramatically change the difficulty of cold environments.
The following modify the Constitution check
+2 Armor Insulation
+5 Cold Weather Outfit
+5 Fur Clothing
+2 Improvised Shelter*
+5 Resistance to Cold
(advantage) dose of Bloodsalt in the last 24 hours, or a heat source (near a fire)
(advantage) huddling with another character (this cannot be done while moving)
*Having shelter and staying put changes the rate of checks from once every 10 minutes to once every hour.
Armor Insulation: a special alchemical treatment for armor [50 gp]
Blood Salt: Blood Salt is mixed into food, and grants advantage on saving throws against cold, and disadvantage on saving throws against fire. A dose lasts 24 hours and costs 1gp.
Cold Weather Outfit: A wool coat, linen shirt, wool cap, heavy cloak, thick pants/skirt and boots. [10gp]
Fur Clothing: Heavy furs that can be worn in addition to a cold weather outfit. Heavy Furs operate as Hide Armor when worn without armor (including any penalties for non-proficiency). [10 gp, 12 lb.]
Improvised Shelter: A snow cave, den, or lean-to.
Snowshoes [2gp]: While wearing snowshoes, deep snow is only difficult terrain. Normally deep snow is difficult terrain that requires an Athletics check to traverse. Donning showshoes takes one minute, and an action to remove.
Snow goggle [2gp]: Snow goggles grant advantage against the effects of blinding effects, and disadvantage of visual perception checks.