Frost dates for Willow Grove NAS, PA
At Willow Grove NAS, the median last spring frost (32°F) is Apr 11 and the median first fall frost is Nov 1, for a typical growing season of 205 days. For a 90% chance that the last frost has passed, wait until Apr 27. Nearby ZIP codes are in USDA hardiness zones 7a to 7b.
- Apr 11Last spring frost (median)50% chance of 32°F after this date
- Apr 27Safer planting date10% chance of 32°F after this date
- Nov 1First fall frost (median)50% chance of 32°F by this date
- 205 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 10 | Apr 24 | May 11 |
| 32°F | Mar 29 | Apr 11 | Apr 27 |
| 28°F | Mar 15 | Mar 30 | Apr 12 |
| 24°F | Mar 1 | Mar 19 | Apr 1 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Oct 6 | Oct 21 | Nov 4 |
| 32°F | Oct 17 | Nov 1 | Nov 17 |
| 28°F | Nov 1 | Nov 13 | Dec 1 |
| 24°F | Nov 7 | Nov 24 | Dec 16 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 158 days | 179 days | 201 days |
| 32°F | 182 days | 205 days | 226 days |
| 28°F | 209 days | 229 days | 254 days |
| 24°F | 228 days | 252 days | 280 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 19044 | 7a | 0 to 5°F | 1 km |
| 19040 | 7a | 0 to 5°F | 4 km |
| 18976 | 7a | 0 to 5°F | 5 km |
| 19002 | 7a | 0 to 5°F | 6 km |
| 19025 | 7b | 5 to 10°F | 6 km |
| 19090 | 7b | 5 to 10°F | 6 km |
| 18974 | 7a | 0 to 5°F | 7 km |
| 18936 | 7a | 0 to 5°F | 7 km |
| 19436 | 7a | 0 to 5°F | 8 km |
| 19001 | 7b | 5 to 10°F | 8 km |
| 19454 | 7a | 0 to 5°F | 8 km |
| 19034 | 7b | 5 to 10°F | 9 km |
| 19437 | 7a | 0 to 5°F | 10 km |
| 19075 | 7b | 5 to 10°F | 10 km |
| 19038 | 7b | 5 to 10°F | 11 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USW00014793, at 40.2000, -75.1500, elevation 110 m (361 ft).
- Data quality: Representative (10+ years), 15 years of freeze data.
- Average days per year at or below 32°F: 92.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Doylestown Airport (15 km)
- Philadelphia NE Airport (18 km)
- Neshaminy Falls (18 km)
- Norristown (19 km)
- Sellersville (22 km)
- Graterford 1 E (24 km)
- Phila Franklin Inst (27 km)
- Phoenixville 1 E (31 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.