Last spring frost
Apr 4
Frost Dates for Philadelphia, PA
First fall frost
Nov 7
Growing season
216 days
Hardiness zone
7b
In an average year around Philadelphia, PA, the last spring frost (32°F) is about Apr 4 and the first fall frost is about Nov 7, giving roughly a 216-day growing season. To be safe most years, wait until Mar 21 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 3 | Apr 17 | Apr 3 |
| Freeze (32°F) | Apr 17 | Apr 4 | Mar 21 |
| Hard (28°F) | Apr 5 | Mar 23 | Mar 8 |
| Severe (24°F) | Mar 26 | Mar 12 | Feb 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 3 | Apr 28 | Apr 23 | Apr 20 | Apr 17 | Apr 14 | Apr 11 | Apr 7 | Apr 3 |
| 32°F | Apr 17 | Apr 13 | Apr 9 | Apr 6 | Apr 4 | Apr 1 | Mar 31 | Mar 27 | Mar 21 |
| 28°F | Apr 5 | Apr 1 | Mar 30 | Mar 26 | Mar 23 | Mar 20 | Mar 17 | Mar 14 | Mar 8 |
| 24°F | Mar 26 | Mar 21 | Mar 17 | Mar 14 | Mar 12 | Mar 9 | Mar 5 | Mar 1 | Feb 24 |
| 20°F | Mar 18 | Mar 12 | Mar 7 | Mar 4 | Mar 1 | Feb 25 | Feb 21 | Feb 16 | Feb 9 |
| 16°F | Mar 6 | Mar 1 | Feb 25 | Feb 19 | Feb 14 | Feb 10 | Feb 5 | Jan 31 | Jan 21 |
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 12 | Oct 27 | Nov 9 |
| Freeze (32°F) | Oct 24 | Nov 7 | Nov 22 |
| Hard (28°F) | Nov 4 | Nov 19 | Dec 5 |
| Severe (24°F) | Nov 14 | Dec 2 | Dec 23 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 12 | Oct 17 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 5 | Nov 9 |
| 32°F | Oct 24 | Oct 29 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 16 | Nov 22 |
| 28°F | Nov 4 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 22 | Nov 26 | Dec 1 | Dec 5 |
| 24°F | Nov 14 | Nov 21 | Nov 25 | Nov 29 | Dec 2 | Dec 5 | Dec 9 | Dec 15 | Dec 23 |
| 20°F | Nov 28 | Dec 4 | Dec 8 | Dec 13 | Dec 18 | Dec 23 | Dec 28 | Jan 1 | Jan 7 |
| 16°F | Dec 10 | Dec 19 | Dec 26 | Jan 1 | Jan 3 | Jan 7 | Jan 12 | Jan 18 | Jan 30 |
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: Philadelphia Ne Ap, Pa, about 1 miles away@if(!empty($station['elevation_ft'])), at 100 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 Philadelphia, PA?
On average, the last spring frost (32°F) around Philadelphia, PA is about Apr 4. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 21.
When is the first frost in the fall?
The first fall frost around Philadelphia, PA typically arrives about Nov 7. 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 4 on average, or Mar 21 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 216 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 19114 Planting calendar → Pennsylvania frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026