There are "Rainbarrel only" versions and "Project Realism" versions that focus on melting snow for drinking water. General Concept: Melting Snow for Water
It allows Rain Collectors and Metal Barrels to be filled while it is snowing.
It is essential for "winter storm" or "Cryogenic Winter" playthroughs where natural liquid water is scarce.
Snow typically fills containers at a slower rate (often 50% ) compared to rain.