Southeastern Pennsylvania
Philadelphia sits where cold air trapped against the Appalachians meets milder coastal air, which makes ice a more common problem here than deep snow. The estimate below is loaded with live Philadelphia forecast data.
Live Philadelphia forecast estimate
Enter a location to compare tomorrow's snow, ice, temperature, wind and morning timing.
Local conditions
Southeastern Pennsylvania occupies an awkward position in winter. It is close enough to the Atlantic for marine air to reach it, but the Appalachians to the northwest dam cold air at the surface against their eastern slopes. When milder air rides in above that trapped layer, precipitation falls through it and freezes on contact, producing sleet and freezing rain rather than snow. The gradient across the metro is steep: the northern and western suburbs can be all snow while the city and southern New Jersey get rain, with a narrow icing band in between.
What actually drives a decision
A glaze of freezing rain defeats plowing entirely and makes sidewalks, steps and bridges hazardous almost immediately. Because it produces no depth, it can look trivial in a snowfall forecast while being the most disruptive outcome available. Check whether the snow-and-ice factor cites an icing signal rather than accumulation.
The difference between the Philadelphia city limits and the northern suburbs can be the difference between rain and plowable snow. Enter the location nearest the school rather than relying on a regional forecast, and expect the boundary position to be revised as a storm approaches.
A large share of School District of Philadelphia students travel by public transit or on foot. Sidewalk and crossing conditions before dawn therefore carry weight comparable to road conditions, and pedestrian surfaces are cleared later than arterial streets.
Even in an all-snow event, temperatures close to freezing mean wet snow that compacts and partially melts on treated surfaces. That reduces accumulation but raises the refreeze risk overnight, which is a different hazard with a different timing profile.
The forecast for the coordinates above is scored against six weighted factors: snow and ice, temperature, wind chill, morning timing, area and routes, and school level. Around Philadelphia the rows that most often carry the number are temperature, snow and ice. Every factor appears in the result with its own value, score bar and published weight, so a percentage is never presented without the reasoning behind it. The methodology page documents each threshold, and the accuracy and limitations page sets out what the model cannot observe.
This site does not publish closure thresholds for any school system, because those are operational judgements rather than published numbers. What it can do is point you at the organisations that actually decide. Around Philadelphia, PA those include:
Treat the estimate on this page as a reason to prepare and to keep checking, never as an announcement. A school system can close buildings, delay the start, cancel transportation only, dismiss early or move to a different learning format, and those outcomes are not interchangeable.
Primary sources for weather warnings and road conditions covering Philadelphia. School decisions still come from the systems listed above.
Philadelphia questions
No estimate can answer that. The School District of Philadelphia and each suburban district announce separately, and in an icing event the northern and western suburbs frequently close while the city runs a normal or virtual day. Read the district's own message.
Cold air pools at the surface against the eastern slopes of the Appalachians while milder air arrives aloft from the south. Rain falling through that warm layer freezes on cold surfaces. Philadelphia sits close to where that arrangement sets up most often.
Even a thin glaze can make hills, steps, bridges and sidewalks hazardous, and this site does not publish a threshold it cannot verify. Read the National Weather Service ice accumulation forecast, which quantifies expected ice directly.
For locations inside the city, yes. Urban networks are typically treated and restored faster than long rural routes, and the model reflects that with a lower area score. Suburban districts should use Suburban.
Still deciding what to do with the number? Read how schools make the final call and the guide to the best times to check a forecast.