Idaho residents, keep those snow shovels at the ready. Minnesotans, Wisconsinites and Youppers —those who live in Michigan’s Upper Peninsula — should stock up on salt. Those are the parts of the United States where the odds of a White Christmas are highest, according to historical weather data.

The National Oceanic and Atmospheric Administration said that data, from 1981 to 2010, shows most of the Rocky Mountains have a greater than 90 percent chance of waking up on Christmas day with at least an inch of snow on the ground. Parts of northern Minnesota, upstate New York and rural Maine almost always have a snowy Christmas, too.

Here’s their map, showing the historical probability of a White Christmas:

But with nine days to go before Christmas, plenty of usually snowy territory remains uncovered. Data from NOAA’s National Operational Hydrologic Remote Sensing Center (that’s a mouthful) shows no snowpack in Illinois, Indiana and Ohio, and fewer than five centimeters on the ground in Iowa and Nebraska. The historical data shows big patches of all of those states have a 40 to 60 percent chance of a White Christmas.

Here’s the NOHRSC data on current snowpack levels:

No need to worry too much if you live in the South. Most people who live in the region spanning Texas to Florida and north into Kentucky and Virginia have less than a 10 percent chance of having to shovel their sidewalks on Christmas morning.

For those of you in the D.C. area, here’s the Capital Weather Gang’s outlook for our chances of a White Christmas.