Minecraft wiki entry for Windswept_Hills, associated text: The windswept hills biome is the normal variant. This biome features the standard stony and grassy terrain, with a bit of tall grass and sporadically generated oak and spruce trees. As the climate is cold, rainfall changes to snowfall above approximately Y-level 120 where snow layers form on blocks above that point, along with water freezing into ice. They are one of the two places where llamas can spawn, the other place being savanna plateau biomes.