This. There may be weather conditions present or seasonal changes in effect, totally different than what would be natural, within the domains. I think there is one domain where it is constantly winter, with soem werewolf. But it is one of the older modules, form 2e or 1e.It doesn't have winter. There are no seasons in the Shadowfell.
It's a demiplane, one that already replaces many of the rules of a natural world. It doesn't have seasons.
It doesn't have winter. There are no seasons in the Shadowfell.
This. There may be weather conditions present or seasonal changes in effect, totally different than what would be natural, within the domains.
A massive storm front has been building for the last several days, and as the characters enter the cave the sky breaks loose—in addition to the heavy winds, a thick freezing rain begins to fall in torrential bursts, interwoven with inch-wide hailstones. Staying outside will almost certainly bring death to whomever is foolish enough to do so. (p. 21)
The storm causes the temperature to drop very quickly. Characters outside the wolf den take 1d4 points of bludgeoning and cold damage at the start of each of their turns due to the hail and freezing rain; characters wearing cold weather gear take half of this damage. (p. 21)
It is wintertime, and though there are piles of snow here and there, it is currently drizzling. Cold, fat raindrops splatter into the mud and heighten the dreariness. (p. 9)
There are not very many residents in Orașnou, and all the other able-bodied men and women are preparing the village for the coming winter. (p. 10)
Once the storm hits, at the beginning of each encounter each character must succeed on a DC 9 Constitution saving throw or gain a level of exhaustion. Creatures with resistance or immunity to cold damage automatically succeed on the saving throw, as do creatures wearing cold weather gear (thick coats, gloves, and the like) and creatures naturally adapted to cold environments. (p. 11)
Seeing as Barovia is a Romanian analogue, what rarely takes into the account that it would most likely have a harsh winter.
How will that change Curse of Strahd and the various encounters that occur?