White Christmas probability map
NOAA's map answers the historical question: how often did a location have at least one inch of snow on the ground on December 25 during the latest 30-year climate-normal period?
Historic probability of at least 1 inch of snow on December 25
The background field is NOAA's interpolated Lower-48 estimate. Station observations anchor the analysis; local terrain can create sharp differences, especially in the West.
Marquette, Michigan: about 96%
NOAA's 1991-2020 material places Marquette among the strongest White Christmas climatologies in the country.
Caribou, Maine: about 87%
Cold northern latitude plus a persistent winter snowpack gives northern Maine a much stronger historical signal than coastal New England.
Flagstaff, Arizona: about 59%
Elevation can overwhelm latitude. High terrain in otherwise warmer states can have a materially higher Christmas snow probability.
Des Moines, Iowa: about 43%
Many central U.S. locations sit in the genuinely uncertain band where the actual year's weather matters more than reputation.
Why the map is useful
It establishes the prior
A 70% historical location and a 10% historical location should not start the season with the same estimate. Climate history is the correct first anchor.
It reveals terrain
Mountain elevations, lake-effect belts and northern latitude produce real spatial structure that a simple state average would hide.
It is not a daily forecast
The map is built from 1991-2020 history. As December 25 enters forecast range, the actual NWS forecast should carry much more weight.