UnrulyOwl's Dreadful Winter

Frost accumulates during snowstorms, and it also gathers gradually in snowy biomes when no storm is present. Above Y 150, ambient frost accumulates in any biome. The frost level rises through three stages, Mild Frost, Severe Frost and a final stage, and each stage applies slowness and freezing effects with particles that show when they are active.

Holding a torch or staying close to a light source keeps a player warm. Once the frost bar becomes full, the cold overtakes the player and freezing effects begin, and they disappear once the frost drains. The mod also affects mobs, and individual features can be enabled or disabled, with the rest customized in its configuration screen. It requires Cloth Config API and optionally uses Mod Menu for that screen. The mod runs on Fabric for 26.1.2 and is released under the MIT License, but the code is not open source.