Philadelphia, Pennsylvania – St. Patrick’s Day week across Pennsylvania could bring a late-season return of winter as colder air descending from Canada increases the potential for snow just days before the start of spring.
According to the NOAA Climate Prediction Center’s 8–14 day outlook, the period from March 15 through March 21 favors above-normal precipitation across the Northeast and Mid-Atlantic, while temperatures across much of the eastern United States trend below seasonal averages. The pattern forms as a large cold boundary drops south from Canada, stretching from Maine across the Great Lakes and down toward Georgia and northern Florida, funneling colder air into the region.
That setup places Philadelphia, Pittsburgh, Harrisburg, Allentown, and Erie in a zone where incoming storm systems could interact with colder air, increasing the chance for late-season snow or rain transitioning to snow during St. Patrick’s Day week.
Drivers along major travel corridors including Interstate 76 (Pennsylvania Turnpike), Interstate 80, Interstate 81, and Interstate 95 should watch for changing conditions if storm systems develop. Even modest snowfall during mid-March can create slick overpasses and reduced visibility during morning commutes.
The timing stands out because daylight saving time begins this weekend, yet winterlike conditions may linger across the Mid-Atlantic even as the first day of spring arrives later that week.
Forecasters expect additional updates as the mid-March pattern becomes clearer, and advisories could follow if coastal storm systems align with the colder air mass across the region.
