Across the Contiguous U.S., you only have a 2% chance of seeing snow on Halloween. The highest chance exists in Colorado's front range. There is a 48% chance of seeing snow in Breckenridge, Colorado, on Halloween, but there is only a 19% chance in Denver.
Across the Upper Midwest and in New England, chances are nearer 11%. Of course, the highest chance of seeing Halloween snow in the U.S. is in Alaska, where many areas have a 60% chance.
Halloween snowstorms are relatively rare, but some notable ones have occurred. While the weather promises to be cold this year in some areas of the country for Halloween, it's unlikely that the weather will match the conditions trick-or-treaters faced during these storms of the past.
Halloween Blizzard 1972
Often called the Halloween Megastorm, the Halloween Blizzard of 1972 dumped 13.8 inches of snow in Colorado Springs, Colorado, but they were far from alone. Some trick-or-treaters in North Dakota and South Dakota had to cope with up to 30 inches of snow.
While the snow started in many areas a day or two before Halloween, the vast majority of snow fell throughout Halloween Day, interfering with many fall festivities. National Guard troops were employed to rescue some motorists as roads became impassable.