This mod is multifunctional. Simply put, it adds numerous visual, auditory, and AI effects based upon weather. Has a character gotten wet? Then the water will drip off of them. Is it cold? You'll see their breath. Is there a blizzard? Then it will be hard for you and them to see and the wind will howl. Of course if the weather's bad, they might just go inside like a sane person would. With this mod, a lot of appropriate properties come into play regarding behavior and physical effects with the weather.
Credits: isoku