Snowfall in your area may be inevitable, but you still want the answer to one question: when should you expect the first flake to fall? Surprisingly, altitude is just as important as latitude. It historically snows in the mountains of Arizona and New Mexico before Chicago.
To estimate the first snow fall in your area, check out the map provided by the National Oceanic & Atmospheric Administration (NOAA). Make sure you order your snow blower this year before winter wages its war against you.