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Record and Average Dates of Late Season Snowfall in the U.S.

By: Christopher C. Burt, 7:21 PM GMT on April 01, 2014

Record and Average Dates of Late Season Snowfall in the U.S.

A late season blizzard has pounded the northern Plains with snowfall of up to 20” in North Dakota. How unusual is this and when can the last measurable snowfall be expected across the country? Here are some interesting maps on the subject created by climate scientist Brian Brettschneider and some examples of incredible late season snowfalls from the pre-USWB era.

A late season blizzard, designated winter storm Xenia by The Weather Channel plastered South Dakota, North Dakota, and portions of Minnesota on March 31st and April 1st. A similar storm, named Xerxes, struck the same area last April depositing similar amounts of snow, as was the case in Dalton, Minnesota pictured above. Photo by Debbie Kaminski.

For some locations in the Upper Midwest and western Great Plains, the 2013-2014 season has been the snowiest on record (details will follow in a future blog). Climatology suggests winter is yet not over for these regions. In fact, for some locations in the Rocky Mountains and western Plains, April is normally the snowiest month of the year. Places like, Casper, Wyoming; Lander Wyoming; Deadwood, South Dakota; and Leadville, Colorado; all experience their snowiest month in April. For those who might be interested in some examples of heavy April snowstorms see my blog ‘Record April Snowstorms published last April (2013).

Sites in the U.S. where, on average, April is the snowiest month of the year. These include the Black Hills of South Dakota and a number of sites in Colorado, Wyoming, and Montana. Of the 4,214 stations in the U.S. for which the National Climate Data Center (NCDC) calculates normal snowfall, and that receive greater than 2” of snow per year, 34 have their snowiest month in April. Brian Brettschneider of Borealis Scientific, LLC.

The map above illustrates which month of the year is normally the snowiest across the entire United States. The data is compiled from the above mentioned 4,214 NCDC sites. The shading on the map is based on the value of up to six nearby points so in a few cases the color may not correspond exactly to the snowiest month. Brian Brettschneider of Borealis Scientific, LLC.

So far as when (during which month) the last measurable snowfall normally occurs we can see in the map below that, for much of New England, the Upper Midwest and Plains, as well as the Rocky Mountain States and higher elevations of other western states, some April snowfall is a norm.

Map of average date of last measurable snowfall across the U.S. In much of Alaska and the Rocky Mountains this doesn’t occur until well into May. The data for the map is derived from the GHCN (v. 3) database and only utilizes primary USW stations with at least 15 years of records since 1980. Brian Brettschneider of Borealis Scientific, LLC.

Of course, there are some years when measurable snowfall occurs well after the ‘normal’ dates as outlined in the map below. This is a map of when the latest measurable snowfalls on record have occurred. As can be seen, June snowfall has occurred at some time in the past in much of the higher elevations of the West and Alaska.

Map above roughly illustrates the dates of occurrence of the latest measurable snowfall on record and uses the same database as the ‘Average Last Measurable Snow Date’ map. For this map, all primary stations were utilized independent of their period of record. Brian Brettschneider of Borealis Scientific, LLC.

Below is a table of latest measurable snowfalls on record for a handful of select cities across the contiguous U.S.:

Some Historic Pre-USWB Late Season Snowstorms

The May 4th Snowstorm of 1774

A general snowfall of around 4” occurred from northern Virginia to southern New England. Both Philadelphia and New York City reported “a considerable quantity of snow”. Thomas Jefferson and George Washington both noted the event in their diaries.

The Great April Fools Day Snow of 1807

Probably the deepest April snowfall in the history of the Ohio Valley and Mid-Atlantic occurred on April 1, 1807 from Illinois to the Northeast. The track of the storm was not the usual coastal nor’easter variety (that normally produces great snowstorms) but rather a low that moved northeast from the lower Tennessee Valley and across the mid-Atlantic states and offshore around New York City. To the north of the storm path incredible snowfalls were reported. The westernmost report we have came from Vincennes on the Illinois-Indiana border with an 11” accumulation but it was in Pennsylvania, New York and New England that astonishing snowfall was reported including: 52” at Montrose, Pennsylvania near Scranton; 54” at Utica, New York, 52” at Lunenburg, Vermont; 60” at Danville, Vermont; 48” at Montpelier, Vermont; and 42-48” at Norfolk, Connecticut.

The June 1816 Snows of the ‘Year without Summer’

Most famous of all cold and snowy late season events would have to be the infamous 1816 ‘Year without Summer’ with snowfall in June that occurred in the eastern U.S. and Canada. On June 6th accumulating snow was observed as far south as the Catskills in New York (where one inch was reported) and highlands of central and northwest Pennsylvania. Snowflakes were seen at sea level as far south as ten miles north of tidewater on the Hudson River, just north of New York City. The deepest accumulations were reported in the mountains of Vermont where drifts of 12”-18” were measured. Quebec City in Canada reported 12” on level with drifts up to two feet deep.

The even Greater Snow of June 1842

It should be noted that June snowfall in the Northeast is not a unique event to 1816. On June 11, 1842 widespread snow fell over northern New York and New England and snowflakes were observed in Cleveland, Ohio; Boston, Massachusetts; and even Harrisburg, Pennsylvania. Accumulations of 10-12” were common in Vermont, so this event may actually have been more extreme than the famous snow of June 1816.

REFERENCES FOR PRE-USWB SNOWFALLS: Early American Winters: Vol 1: 1604-1820 and Vol 2: 1821-1870 by David M. Ludlum, American Meteorological Society, 1966, 1968.

KUDOS: Thanks to Brian Brettschneider of Borealis Scientific, LLC for the maps reproduced above.

Christopher C. Burt
Weather Historian

Extreme Weather Snow

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.