Frost dates for Graterford 1 E, PA
At Graterford 1 E, the median last spring frost (32°F) is Apr 24 and the median first fall frost is Oct 15, for a typical growing season of 173 days. For a 90% chance that the last frost has passed, wait until May 9. Nearby ZIP codes are in USDA hardiness zone 7a.
- Apr 24Last spring frost (median)50% chance of 32°F after this date
- May 9Safer planting date10% chance of 32°F after this date
- Oct 15First fall frost (median)50% chance of 32°F by this date
- 173 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 21 | May 4 | May 21 |
| 32°F | Apr 10 | Apr 24 | May 9 |
| 28°F | Mar 28 | Apr 10 | Apr 27 |
| 24°F | Mar 14 | Mar 30 | Apr 14 |
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 | Sep 21 | Oct 4 | Oct 18 |
| 32°F | Oct 1 | Oct 15 | Nov 1 |
| 28°F | Oct 10 | Oct 27 | Nov 12 |
| 24°F | Oct 23 | Nov 10 | Nov 27 |
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 | 131 days | 151 days | 170 days |
| 32°F | 151 days | 173 days | 193 days |
| 28°F | 174 days | 198 days | 221 days |
| 24°F | 200 days | 226 days | 249 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 |
|---|---|---|---|
| 19474 | 7a | 0 to 5°F | 2 km |
| 19426 | 7a | 0 to 5°F | 5 km |
| 19438 | 7a | 0 to 5°F | 5 km |
| 19473 | 7a | 0 to 5°F | 6 km |
| 19490 | 7a | 0 to 5°F | 7 km |
| 19446 | 7a | 0 to 5°F | 10 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 USC00363437, at 40.2294, -75.4242, elevation 85 m (279 ft).
- Data quality: Representative (10+ years), 16 years of freeze data.
- Average days per year at or below 32°F: 137.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Pottstown Limerick Airport (11 km)
- Phoenixville 1 E (13 km)
- Norristown (15 km)
- Sellersville (17 km)
- Willow Grove NAS (24 km)
- Doylestown Airport (28 km)
- Glenmoore (32 km)
- W Chester 2 NW (34 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.