First Accumulating Snow: Here's When It Typically Arrives Where You Live

October marks the seasonal shift toward the average first accumulating snow of the season in parts of the nation's northern tier and Mountain West, but many other areas have to wait it out until November or December.

Here's how meteorologists define the first accumulating snow: Snow totaling 0.1 inches or more is what qualifies as accumulating snow, also known as measurable snow. It can't just be flurries flying through the air, or snow that falls and immediately melts on contact with the ground.

W​hen that first 0.1-inch snowfall typically arrives: The map below uses data from the National Weather Service to show the month when the average first accumulating snow falls, based on 1991-2020 data. Keep in mind these are averages and any given season can produce its first snowfall either very early or very late, depending on the weather pattern.

I​t generally breaks down into these months:

-September or October: The Rockies to the Northern Plains, northern Great Lakes and northern New England.

-​November or December: Much of the Midwest and Northeast.

W​hy most of the South isn't included in the data shown on the map: Much of the region doesn't see accumulating snow every year. When it does, January and February are, on average, the most favorable months for at least a coating of snow.

H​ere's a closer look at what's typical for each region, along with the specific average first snow date for a few cities.

Northeast and mid-Atlantic average first snow ranges from October to December: October is typically the month's first snow in the mountains of northern New England and the Adirondacks.

The M​idwest's average first snow is in October or November for most: The northern tier, from northern Michigan to the western Dakotas, often sees accumulating snow arrive in October.

In November, much of the Ohio Valley, the rest of the Great Lakes, the mid-Mississippi Valley and the Central Plains join the ranks. Parts of southeast Kansas, southern Missouri and the Lower Ohio Valley typically have to wait until December to see their first accumulating flakes.

T​he West sees accumulating snow earliest because of mountains: Snow can fall over the highest peaks of the Rockies even in summer, but September is considered average from the higher elevations of western Montana into the Colorado Rockies.

Otherwise, October typically heralds the arrival of the season's first flakes in the lower elevations of Montana, Wyoming, the Wasatch, Colorado's foothills and mountain valleys, and the mountains of northern New Mexico.

November's first snow is typical from the plains of southeast Colorado into the rest of northern New Mexico, northern Arizona (Flagstaff), portions of the Great Basin and the interior Northwest.

The threat of snow is not usually a factor in places like Seattle and Portland, Oregon, until late December.

A closer look at the South's most likely time for accumulating snow: For more southern locations, such as Atlanta and Dallas, instead of mentioning an average first date of measurable snow, we specify an average time frame during which you can expect the best chance of measurable snow each year, defined by the average first and last dates of measurable snow. This is typically in January and February from the Carolinas to northern Texas.

The Texas Panhandle and the highest elevations of the southern Appalachians are exceptions. Those areas can expect their first snow in November or December.

Valley locations of the southern Appalachians, parts of northern and Middle Tennessee, northern Arkansas, and central and eastern Oklahoma can see their first dusting of snow sometime in December, if at all.

Chris Dolce has been a senior meteorologist with weather.com for over 10 years after beginning his career with The Weather Channel in the early 2000s.