Snowy

The Snowy mod can turn any Minecraft seed into a icy world. With this mod installed, every biome in your game will be covered in snow. And it will snow instead of rain. Note that the biomes where there is naturally no rain, like deserts, will not snow. 

Take a look at the screenshots to see what you can expect from this mod. This is a Fabric mod and download links are given below. Read the installation instructions carefully.