Terraria - Snow Biome

Snow biomes are present in 1/3 of all the worlds at any given time. But in the worlds created during the period between 15th and 31st December, it generates in all the worlds. Snow Blocks replace Grass and Dirt in this biome. This biome is similar to Forests with respect to enemies. Although, unlike Forests, Hallow and Corruption spread does not spread in this biome.