Last spring frost
Apr 16
Frost Dates for Harwick, PA
First fall frost
Nov 1
Growing season
197 days
Hardiness zone
6b
In an average year around Harwick, PA, the last spring frost (32°F) is about Apr 16 and the first fall frost is about Nov 1, giving roughly a 197-day growing season. To be safe most years, wait until Mar 31 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | May 17 | Apr 29 | Apr 13 |
| Freeze (32°F) | May 4 | Apr 16 | Mar 31 |
| Hard (28°F) | Apr 19 | Apr 3 | Mar 19 |
| Severe (24°F) | Apr 6 | Mar 24 | Mar 8 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 17 | May 10 | May 5 | May 2 | Apr 29 | Apr 26 | Apr 22 | Apr 18 | Apr 13 |
| 32°F | May 4 | Apr 27 | Apr 23 | Apr 20 | Apr 16 | Apr 12 | Apr 8 | Apr 5 | Mar 31 |
| 28°F | Apr 19 | Apr 14 | Apr 9 | Apr 6 | Apr 3 | Apr 1 | Mar 29 | Mar 24 | Mar 19 |
| 24°F | Apr 6 | Apr 2 | Mar 30 | Mar 27 | Mar 24 | Mar 21 | Mar 18 | Mar 14 | Mar 8 |
| 20°F | Mar 29 | Mar 24 | Mar 20 | Mar 17 | Mar 14 | Mar 11 | Mar 8 | Mar 4 | Feb 27 |
| 16°F | Mar 22 | Mar 17 | Mar 13 | Mar 10 | Mar 6 | Mar 2 | Feb 28 | Feb 22 | Feb 13 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Oct 7 | Oct 20 | Nov 1 |
| Freeze (32°F) | Oct 18 | Nov 1 | Nov 13 |
| Hard (28°F) | Nov 1 | Nov 11 | Nov 25 |
| Severe (24°F) | Nov 7 | Nov 20 | Dec 9 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 7 | Oct 11 | Oct 14 | Oct 17 | Oct 20 | Oct 22 | Oct 25 | Oct 28 | Nov 1 |
| 32°F | Oct 18 | Oct 22 | Oct 26 | Oct 29 | Nov 1 | Nov 2 | Nov 5 | Nov 9 | Nov 13 |
| 28°F | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 11 | Nov 14 | Nov 17 | Nov 21 | Nov 25 |
| 24°F | Nov 7 | Nov 11 | Nov 14 | Nov 17 | Nov 20 | Nov 24 | Nov 28 | Dec 2 | Dec 9 |
| 20°F | Nov 13 | Nov 19 | Nov 24 | Nov 28 | Dec 1 | Dec 7 | Dec 12 | Dec 18 | Dec 24 |
| 16°F | Nov 24 | Dec 1 | Dec 7 | Dec 13 | Dec 18 | Dec 23 | Dec 27 | Jan 1 | Jan 8 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Acmetonia Lock 3, Pa, about 1.5 miles away@if(!empty($station['elevation_ft'])), at 748 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Harwick, PA?
On average, the last spring frost (32°F) around Harwick, PA is about Apr 16. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 31.
When is the first frost in the fall?
The first fall frost around Harwick, PA typically arrives about Nov 1. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Apr 16 on average, or Mar 31 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 197 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 15049 Planting calendar → Pennsylvania frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026