St. Patrick’s Day week in Pennsylvania might bring a late-season return of winter as colder air descends from Canada, increasing the chance of snow only days before spring begins.
According to the NOAA Climate Prediction Center’s 8-14 day forecast, the period from March 15 to March 21 favors above-normal precipitation in the Northeast and Mid-Atlantic, while temperatures in much of the eastern United States trend below seasonal averages. The pattern arises when a strong cold boundary drops south from Canada, reaching from Maine across the Great Lakes to Georgia and northern Florida, funneling colder air into the area.
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That configuration puts Philadelphia, Pittsburgh, Harrisburg, Allentown, and Erie in a zone where approaching storm systems may interact with cooler air, boosting the likelihood of late-season precipitation or rain converting to snow throughout St. Patrick’s Day week.
Drivers on important travel corridors such as Interstate 76 (Pennsylvania Turnpike), Interstate 80, Interstate 81, and Interstate 95 should be aware of shifting circumstances as storm systems develop. Even light snowfall in mid-March can result in slick overpasses and impaired visibility during morning commutes.
The timing is noteworthy because daylight saving time begins this weekend, but winter-like weather may persist across the Mid-Atlantic even when the first day of spring arrives later that week.
Forecasters anticipate more changes as the mid-March pattern becomes apparent, and advisories may follow if coastal storm systems align with the colder air mass throughout the region.
