Maps: When Does Your City Usually See Its First Snowfall?
People keep calling these early-season snows "unprecedented" when they're really not. What is the earliest it's ever snowed, and when does it usually start snowing? Let's take a look at some data from major cities around the country to settle the question.
Winter reminds us all that social media is the most effective means of rewriting history available to mankind. Snow didn't come into being when Mark Zuckerberg said "let there be data mining." Our weather records often go back into the early 1900s and even late 1800s in some cases. It's snowed in early November. It's snowed in October. Heck, in many places in the Upper Midwest, it's snowed in September!
Snow this early in the year is unusual, yes, but it's rarely "unprecedented." Here are some maps I hastily threw together to drive home the point that, while snow this early in the year isn't common, it's also not unheard of. The data presented below takes into account measurable snowfall (that is, 0.1" or more) at a city's major airport. For the sticklers, I used National Airport for D.C., Central Park for NYC, and the old Stapleton Airport for Denver because it has a longer record and is more centrally located than DIA.
The average first snowfall across parts of the Ohio Valley and I-95 Corridor generally follows the pattern one would expect for the region—November snows west of the Appalachians, with earlier snow falling around the Great Lakes. D.C., Philly, and New York often don't see their first snows until December—they usually get a few small blankets of snow before their biggest wallopings come in January through March.
Snow is harder to come by in the southern United States, but residents are no strangers to the white stuff. The first snow of the year usually falls in January from Little Rock east through Raleigh, with the average first snow falling a little earlier on the Plains. Every city listed has seen snow in November—even Austin, recording 2.0" of snow on November 8, 1955.
Due to their proximity to America's Air Conditioner, areas from the northern Rockies east through the Great Lakes often see snow much earlier in the year than the rest of the country. The average first snowfall occurs in October or November, with measurable snow falling as early as September 7 in south-central Montana. Last year was the snowiest year on record in Rapid City, South Dakota, in large part due to a major blizzard that dumped up to two feet of snow on the area on October 4-5.
I didn't make a map for the West Coast because snow is so rare in major cities along the Pacific. In Seattle (KSEA), at least, the average first snow occurs on December 19, and the earliest the city has seen measurable snowfall was October 27, 1971 (2.0").
Portland Int'l Airport rarely sees large snowstorms*, downtown San Francisco has only measured snow twice (1933 and 1952), and downtown Los Angeles has only seen snow four times. In the handful of times it's snowed in Las Vegas, the earliest was November 15, 1964 (3.0").
@JimCantore Our trusty snow observer in Gile, WI has provided us with this picture. 48.3 inches & counting since Mon pic.twitter.com/dJQgAwoZnQ
— NWS Duluth (@NWSduluth) November 14, 2014
Even on the extreme side of things, this kind of snow in November isn't unprecedented. Residents of Gile, Wisconsin (near Lake Superior) are digging out from nearly fifty (five-zero!) inches of lake effect snow that's fallen since early last week. That isn't the most snow the region has seen in the month of November—in neighboring Ironwood, the record is 78.2" set in 1989, followed by 60.7" (1995), 56.9" (1991), 52.0" (1959), and 51.6" (1956). If no further snow falls this month, this November will go down as the tenth snowiest on record in Ironwood.
Winter is here. Bring it on.
[Image via AP, maps by the author]
*Correction: This post previously stated that Portland, OR hasn't seen an inch of snow since the 1990s. Historical data kept by NOAA doesn't correctly record snow at Portland Int'l Airport, so the information I referenced was wrong, and so was I. The city saw nearly 8 inches of snow in February 2014. I apologize for the error.