Winter is coming. As a backcountry skier every year I wait for it the whole summer. If you’re also waiting for the first snowfall, you will like the map recently released by the National Oceanic and Atmospheric Administration (NOAA).

The map shows historical data of the first day of snow for an average year across cities in the US. It gives us skiers an idea of where to find early snow to start a winter season. The map is based on 1981-2010 historical patterns. “It isn’t the average date of the first observed snowfall. Technically, it’s the date by which there’s a 50% chance at least 0.1” of snow will have accumulated”, we read on the project’s website.

There are some obvious trends in the map. First of all the snowfall depends on latitude and altitude. The farther north and the further up you are the earlier you may see snow.

“The highest elevation stations along the spines of the Rockies have a year-round threat of snow. On the other end of the spectrum, the Deep South, Gulf Coast, Desert Southwest and Hawaii have many stations that get snow so infrequently, there’s no date listed (empty circles). In these places, there just aren’t enough events to make robust statistics.”

Cartographically speaking the map is not beautiful but it serves its purpose well. The “cloud” of dense points makes at that scale a kind of a heat map. Cool.

source: NOAA