Frost dates for 19187Philadelphia, PA
The average last spring frost in Philadelphia is March 30 and the average first fall frost is November 17, giving a typical growing season of about 232 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 30
- Average first fall frost
- Nov 17
- Growing season
- 232 days
Safer after Apr 12 (1-in-10 risk)
Possible by Nov 4 (1-in-10 risk)
First frost typically in 14 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Mar 27 · Apr 8 · Apr 23 | Oct 23 · Nov 5 · Nov 20 | 211 days | 100% |
| Frost / freeze (32°F) | Mar 15 · Mar 30 · Apr 12 | Nov 4 · Nov 17 · Dec 4 | 232 days | 100% |
| Hard freeze (28°F) | Mar 1 · Mar 17 · Mar 31 | Nov 12 · Nov 29 · Dec 18 | 257 days | 100% |
Planting calendar for Philadelphia
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Feb 27 – May 5 |
| Tomatoes | Transplant outdoors | Apr 15 – Jul 28 |
| Peppers | Start seeds indoors | Feb 27 – Mar 30 |
| Peppers | Transplant outdoors | Apr 29 – May 30 |
| Eggplant | Start seeds indoors | Mar 16 – Apr 14 |
| Eggplant | Transplant outdoors | Apr 29 – May 30 |
| Cucumbers | Sow outdoors | Apr 29 – Aug 7 |
| Summer squash | Sow outdoors | Apr 15 – May 30 |
| Winter squash & pumpkins | Sow outdoors | Apr 29 – May 30 |
| Snap beans | Sow outdoors | Apr 15 – Aug 30 |
| Sweet corn | Sow outdoors | Apr 15 – Jul 28 |
| Watermelon & cantaloupe | Sow outdoors | Apr 29 – May 30 |
| Okra | Sow outdoors | Apr 22 – May 15 |
| Peas | Sow outdoors (spring) | Feb 27 – Apr 14 |
| Potatoes | Plant outdoors (spring) | Feb 27 – Apr 29 |
| Onions | Start seeds indoors (spring) | Jan 16 – Feb 12 |
| Onions | Transplant outdoors (spring) | Mar 16 – Apr 14 |
| Broccoli | Start seeds indoors (spring) | Feb 9 – Mar 15 |
| Broccoli | Transplant outdoors (spring) | Mar 16 – Apr 14 |
| Broccoli | Start seeds indoors (fall) | Jul 18 – Jul 28 |
| Broccoli | Transplant outdoors (fall) | Aug 17 – Aug 28 |
| Cabbage | Start seeds indoors (spring) | Jan 30 – Feb 27 |
| Cabbage | Transplant outdoors (spring) | Feb 27 – Mar 30 |
| Cabbage | Start seeds indoors (fall) | Jul 8 – Aug 7 |
| Cabbage | Transplant outdoors (fall) | Aug 7 – Sep 7 |
| Leaf lettuce | Sow outdoors (spring) | Feb 27 – May 15 |
| Leaf lettuce | Sow outdoors (fall) | Aug 7 – Sep 23 |
| Spinach | Sow outdoors (spring) | Feb 20 – Apr 5 |
| Spinach | Sow outdoors (fall) | Aug 24 – Sep 28 |
| Radishes | Sow outdoors (spring) | Feb 27 – Apr 19 |
| Radishes | Sow outdoors (fall) | Aug 7 – Oct 8 |
| Kale | Sow outdoors (spring) | Mar 16 – Apr 5 |
| Kale | Sow outdoors (fall) | Jul 31 – Sep 7 |
| Carrots | Sow outdoors (spring) | Mar 30 – May 15 |
| Carrots | Sow outdoors (fall) | Jul 8 – Aug 23 |
| Garlic | Plant outdoors (fall) | Nov 7 – Dec 8 |
Where these dates come from
ZIP code 19187 is matched to the NOAA station Phila Franklin Inst, PA, 1 km away, at 60 ft elevation (24 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Phila Franklin Inst, PA (used) | 60 ft | Mar 30 | Nov 17 |
| Philadelphia Intl Ap, PA | 10 ft | Apr 2 | Nov 10 |
| Pennsauken 1N, NJ | 46 ft | Apr 15 | Oct 31 |
| Moorestown, NJ | 45 ft | Apr 12 | Nov 1 |
Frost dates near Philadelphia
- Philadelphia, PA 19099 · last Mar 30, first Nov 17
- Camden, NJ 08102 · last Mar 30, first Nov 17
- Gloucester City, NJ 08030 · last Mar 30, first Nov 17
- Oaklyn, NJ 08107 · last Apr 15, first Oct 31
- Lansdowne, PA 19050 · last Mar 30, first Nov 17
- Upper Darby, PA 19082 · last Mar 30, first Nov 17
- Bala Cynwyd, PA 19004 · last Mar 30, first Nov 17
- Pennsauken, NJ 08110 · last Apr 15, first Oct 31
Frequently asked questions
- When is the last frost in Philadelphia, PA?
- For ZIP code 19187, the average last spring frost (32°F) is March 30, based on NOAA 1991-2020 climate normals for the Phila Franklin Inst, PA weather station. There is a 1-in-10 chance of a frost after April 12.
- When is the first frost in Philadelphia, PA?
- The average first fall frost (32°F) is November 17. There is a 1-in-10 chance of frost by November 4, so tender plants are at risk from that point on.
- How long is the growing season in 19187?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 232 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.