Frost dates for Dehart Dam, PA
At Dehart Dam, the median last spring frost (32°F) is May 1 and the median first fall frost is Oct 16, for a typical growing season of 168 days. For a 90% chance that the last frost has passed, wait until May 20. Nearby ZIP codes are in USDA hardiness zones 6b to 7a.
- May 1Last spring frost (median)50% chance of 32°F after this date
- May 20Safer planting date10% chance of 32°F after this date
- Oct 16First fall frost (median)50% chance of 32°F by this date
- 168 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 26 | May 12 | May 27 |
| 32°F | Apr 15 | May 1 | May 20 |
| 28°F | Apr 1 | Apr 18 | May 8 |
| 24°F | Mar 17 | Apr 1 | Apr 19 |
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 23 | Oct 5 | Oct 18 |
| 32°F | Oct 3 | Oct 16 | Nov 1 |
| 28°F | Oct 10 | Oct 30 | Nov 13 |
| 24°F | Oct 26 | Nov 11 | Nov 30 |
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 | 127 days | 145 days | 166 days |
| 32°F | 145 days | 168 days | 190 days |
| 28°F | 169 days | 194 days | 218 days |
| 24°F | 200 days | 223 days | 245 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 |
|---|---|---|---|
| 17032 | 6b | -5 to 0°F | 7 km |
| 17018 | 7a | 0 to 5°F | 8 km |
| 17028 | 7a | 0 to 5°F | 9 km |
| 17112 | 7a | 0 to 5°F | 10 km |
| 17980 | 6b | -5 to 0°F | 11 km |
| 17097 | 6b | -5 to 0°F | 14 km |
| 17048 | 6b | -5 to 0°F | 14 km |
| 17023 | 6b | -5 to 0°F | 14 km |
| 17030 | 6b | -5 to 0°F | 16 km |
| 17005 | 6b | -5 to 0°F | 17 km |
| 17061 | 7a | 0 to 5°F | 17 km |
| 17098 | 6b | -5 to 0°F | 17 km |
| 17978 | 6b | -5 to 0°F | 19 km |
| 17069 | 7a | 0 to 5°F | 20 km |
| 17968 | 6b | -5 to 0°F | 23 km |
| 17957 | 6b | -5 to 0°F | 25 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 USC00362071, at 40.4608, -76.7486, elevation 164 m (537 ft).
- Data quality: Representative (10+ years), 20 years of freeze data.
- Average days per year at or below 32°F: 128.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Harrisburg 1 NE (22 km)
- Lebanon 2 W (28 km)
- Harrisburg Cptl Cy Airport (28 km)
- Middletown Harrisburg Intl Airport (30 km)
- Selinsgrove 2 S (37 km)
- Selinsgrove Penn Valley Airport (41 km)
- Sunbury (44 km)
- Bear Gap (45 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.