Gone are the 60-degree temperatures from Thursday, now replaced by high temperatures near the 32-degree mark.
The return of colder air was accompanied by a couple of inches of snow early Friday night with snowfall accumulations generally between 2 and 4 inches across the area.
As temperatures fall, a layer of ice may form underneath the snow, adding to driving and walking conditions.
The weekend will be cold around Pittsburgh with high temperatures within a few degrees of freezing.
After a break from precipitation on Saturday, another round of snow and a wintry mix is in the offing for Sunday.
The coldest air of the season so far may follow during the middle of next week.
Unsettled weather for the extended Labor Day weekend will be across the Southeast, Upper Midwest, northern Rockies and the Four Corners.
Tropical Depression 14-E is several hundred miles southwest of Mexico and is expected to strengthen slowly into a tropical storm.
A stormy weather pattern will prevail through September across much of southern South America.
While lulls in tropical activity in the Atlantic will continue, a rapid end to the hurricane season in September does not always occur during an El Niño.
The combination of moisture from Erika and a non-tropical system will drench areas from Florida to the South Carolina coast through the middle of the week.
Heat will be erased by an autumnlike air mass across parts of northern Europe.
Tampa, FL (1935)
The "Labor Day" hurricane hit Tampa, killing 400 people. Earlier, this intense storm had a center barometric pressure of 26.35 inches - the lowest recorded sea level pressure in the Western Hemisphere.
Denver, CO (1961)
Earliest snow on record; a total of 4.2 inches. A great storm raged at high elevations with 2-3 feet of snow closing roads on Labor Day weekend.
Coffeyville, KS (1970)
Hailstone 17.5/44 cm in circumference 1.671 lb/757 gm.