Why does Niseko get so much snow?
Niseko is covered in snow from late November to mid-April because of the northwesterly monsoon or seasonal winds that come from Siberia.
The winds are extremly dry, cold and consistent due to the fact that Siberia is a large land mass and quite a lot colder than the ocean, causing a northwesterly "off-shore" wind from October to April.
Hokkaido's position right in the the path of this wind in the middle of a relatively warmer water mass, the Japan Sea to the west and the Pacific Ocean to the east, is perfect becasue as the dry cold wind crosses the relatively warmer Japan Sea it picks up moisture.
The Niseko mountains then add the lift the wind needs to produce almost daily orographic snowfall.