Can pigs and other animals spawn on snow-covered dirt? Can creepers and other monsters spawn on snow-covered blocks?
Snow coverage does not affect spawning at all. To be more precise, mobs will spawn as if blocks of snow-cover are blocks of air.
Grave digging this bad boy as it was a question I was looking for an answer for just now, mobs won't spawn when there are 2-7 layers of snow
Snow Golems, but they don't attack players. :(