Frost dates in Philadelphia, Pennsylvania
NOAA 1991–2020 normals for a 32 °F freeze. Low spots and the edge of town run colder than downtown.
Short answer
The average last spring frost in Philadelphia is April 4, and the average first fall frost is November 7, from NOAA's Philadelphia Ne Airport station, 8 miles from the middle of Philadelphia. 1 year in 10 the last frost comes after April 17, and the first one by October 24. That leaves about 217 frost-free days. Philadelphia is in USDA planting zone 7b.
Weather stations around Philadelphia
The first row is the date most people in Philadelphia go by. The others show how far the dates move across the area.
| Station | Last spring frost | First fall frost | Frost-free |
|---|---|---|---|
| Philadelphia Ne Airport 8 mi away, 100 ft | April 4 1 in 10 after April 17 | November 7 1 in 10 by October 24 | 217 days |
| Phila Franklin Inst 4 mi away, 60 ft | March 30 1 in 10 after April 12 | November 17 1 in 10 by November 4 | 232 days |
| Pennsauken 1N 7 mi away, 46 ft | April 15 1 in 10 after May 1 | October 31 1 in 10 by October 16 | 199 days |
| Moorestown 10 mi away, 45 ft | April 12 1 in 10 after May 3 | November 1 1 in 10 by October 17 | 203 days |
| Philadelphia Intl Airport 11 mi away, 10 ft | April 2 1 in 10 after April 13 | November 10 1 in 10 by October 30 | 222 days |
Distances are from the middle of Philadelphia as the Census Bureau maps it. The average date is NOAA's 50% date: half of years have a later last frost, or an earlier first one. Plan by the 1-in-10 date if a freeze would cost you plants. The planting zone is the USDA 2023 zone for ZIP code 19140, at the middle of the city.
Your exact ZIP code
Philadelphia covers a lot of ground. For the station nearest your own street, and its planting zone, type your ZIP code.
How these dates work
Frost dates come from NOAA's 1991 to 2020 Climate Normals, which work out from each weather station's daily lows how likely the last spring freeze and the first fall freeze (32 °F) are by each date. We use the station nearest the middle of your ZIP code and show its height and distance, since a station on a hill or by a lake can differ from your yard.
The average date is the 50% date: half of years have a freeze after the spring date or before the fall one. The 1-in-10 dates are NOAA's 10% dates, the ones to plan by if a late freeze would cost you plants. Within one yard, cold air pools in low spots while walls and paving hold heat, so some corners freeze before others.
More frost dates
All of Pennsylvania, station by station.
Other Pennsylvania cities: Pittsburgh
Nearby: Elizabeth, NJ · Newark, NJ · Jersey City, NJ
Where the numbers come from
- USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture
- PRISM Climate Group, Oregon State University (zone data)
- NOAA NCEI, U.S. Climate Normals 1991–2020, annual/seasonal
- NOAA, Normals calculation methodology (frost-freeze probability dates)
- US Census Bureau, 2025 ZCTA gazetteer (ZIP code centers)
- US Census Bureau, 2025 city population estimates and place gazetteer