Frost dates for Allentown Intl Airport, PA
At Allentown Intl Airport, the median last spring frost (32°F) is Apr 20 and the median first fall frost is Oct 24, for a typical growing season of 184 days. For a 90% chance that the last frost has passed, wait until May 6. Nearby ZIP codes are in USDA hardiness zones 6b to 7a.
- Apr 20Last spring frost (median)50% chance of 32°F after this date
- May 6Safer planting date10% chance of 32°F after this date
- Oct 24First fall frost (median)50% chance of 32°F by this date
- 184 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 19 | May 2 | May 18 |
| 32°F | Apr 6 | Apr 20 | May 6 |
| 28°F | Mar 23 | Apr 5 | Apr 18 |
| 24°F | Mar 10 | Mar 26 | Apr 6 |
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 29 | Oct 12 | Oct 28 |
| 32°F | Oct 8 | Oct 24 | Nov 6 |
| 28°F | Oct 19 | Nov 4 | Nov 18 |
| 24°F | Nov 1 | Nov 16 | Dec 3 |
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 | 142 days | 161 days | 182 days |
| 32°F | 163 days | 184 days | 204 days |
| 28°F | 190 days | 211 days | 229 days |
| 24°F | 214 days | 234 days | 256 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 |
|---|---|---|---|
| 18032 | 7a | 0 to 5°F | 2 km |
| 18109 | 7a | 0 to 5°F | 2 km |
| 18052 | 7a | 0 to 5°F | 5 km |
| 18018 | 7a | 0 to 5°F | 5 km |
| 18102 | 7a | 0 to 5°F | 5 km |
| 18017 | 7a | 0 to 5°F | 5 km |
| 18067 | 7a | 0 to 5°F | 8 km |
| 18037 | 7a | 0 to 5°F | 9 km |
| 18104 | 7a | 0 to 5°F | 9 km |
| 18103 | 7a | 0 to 5°F | 10 km |
| 18020 | 7a | 0 to 5°F | 11 km |
| 18059 | 7a | 0 to 5°F | 11 km |
| 18086 | 6b | -5 to 0°F | 13 km |
| 18014 | 6b | -5 to 0°F | 13 km |
| 18078 | 6b | -5 to 0°F | 15 km |
| 18049 | 7a | 0 to 5°F | 15 km |
| 18065 | 6b | -5 to 0°F | 15 km |
| 18038 | 6b | -5 to 0°F | 16 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 USW00014737, at 40.6508, -75.4492, elevation 119 m (390 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 118.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Springtown 1 NNE (17 km)
- Rodale Rsch Center (26 km)
- Bucksville (27 km)
- Lehighton 1ssw (28 km)
- Sellersville (35 km)
- Doylestown Airport (45 km)
- E Stroudsburg (45 km)
- Pottstown Limerick Airport (47 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.