One of the largest snowstorms in Philadelphia's history occurred on February 12th-14th, 1899 as 18.9" of snow fell over a nearly 40 hour period of time. This storm came on the heels of one of the strongest cold outbreaks in the city's history. Temperatures on February 10th and 11th bottomed out at six degrees below zero, with the high on February 10th only getting to five degrees above zero, which is the coldest daytime high on record (since 1874) in the city. The combined average temperature of a half degree below zero ties February 11th, 1934 for coldest average temperature for a day.
The 1899 cold outbreak was so epic that the only subzero low in Florida's history was reached on February 13th, at two below in Tallahassee and Washington, DC, set their all-time record low at fifteen below on February 11th. The cold wave actually had its origins in the West earlier in the month, with record lows set in Iowa, Michigan, and in the Prairie Provinces of Canada. The three subzero mornings in Philadelphia (9th-11th) were the first of two occurrences (1985 the other) where the low bottomed out below zero on three straight mornings.
US Daily Weather Map Archive, with the second set on the left from Paul Kocin's great write-up on the cold wave of 1899 and the associated blizzard it brought.
With the storm, snowfall totals ranged from about a foot in Scranton and in the Poconos to fifteen inches around the Lehigh Valley. In Philly, 18.9" fell over three days while some of the immediate suburbs picked up as much as 25". Two locations...one in Chester County and then Cape May...both recorded over thirty inches of snow from the storm. Washington ended up with over twenty inches from the storm...all impressive totals. It even snowed in Florida from "Gulf Effect" snow as cold air streamed in over the less chilly Gulf of Mexico waters.
The cold wave, which gripped tightly through the 15th as low temperatures in Philadelphia were only 11 degrees after the storm departed, gradually eased and temperatures rebounded tremendously. Kocin notes that Washington, which had nearly three feet of snow on the ground in the wake of the blizzard, lost its snow pack in about a week's time as temperatures bounced to 61 degrees. In Philadelphia, the bounce was not quite as dramatic but temperatures went from a low of 11 on the 15th to a high of 50 on the 20th and to as high as 57 degrees by the 22nd. The returning mild air put an abrupt end to the snow and cold of what was one of the most impressive cold snaps in recorded history for the US and quickly melted a major snowstorm's impact in rather short duration.