Looking at snowstorms of 10" or more by day of the week (there have been 54 since 1900) reveals Friday to be the day most likely to pick up this type of hefty accumulation (nine times). By contrast, Thursday has never had a snowfall this big; the greatest accumulation has been 9.8", which happened twice - in February 1934 and most recently in the winter of 2018 (Jan. 4). And although a snowstorm that dumped 20.9" in February 2010 started on a Thursday, less than half of the total (9.4") fell on that day.
About two-thirds of the snowstorms in this analysis started on one day and ended the following day (and one storm in February 1920 had significant accumulations on three days). Of the snowstorms which continued into the next day, the storm with the most significant accumulation on each day was the snowstorm of Feb. 25-26, 2010, which saw 9.4" fall on Thursday and 11.5" on Friday.
New York's three biggest snowstorms each occurred on a different day of the week (and a different month): The biggest snowfall of all time, in January 2016, occurred on a Saturday; the second greatest accumulation, in February 2006, took place mostly on a Sunday; and the third-ranked snowstorm, in December 1947, buried the City on a Friday.
One calendar date, Feb. 17, is shared by two Monday snowstorms (in 1902 and 2003); another, Feb. 10, is shared by two on Wednesday (in 1926 and 2010); and Feb. 11 has been the date of two Friday snowstorms (in 1983 and 1994). Finally, there has been a 10"+ accumulation on the same day of the week in consecutive winters just once. It happened on a Monday during the winters of 1978 and 1979, when 15.5" fell on Feb. 6, 1978 and 12.7" fell on Feb. 19, 1979.