Frost dates for 17127Harrisburg, PA
The average last spring frost in Harrisburg is April 9 and the average first fall frost is November 1, giving a typical growing season of about 205 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 9
- Average first fall frost
- Nov 1
- Growing season
- 205 days
Safer after Apr 25 (1-in-10 risk)
Possible by Oct 16 (1-in-10 risk)
Last frost typically in 157 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) | Apr 9 · Apr 22 · May 10 | Oct 7 · Oct 20 · Nov 3 | 180 days | 100% |
| Frost / freeze (32°F) | Mar 27 · Apr 9 · Apr 25 | Oct 16 · Nov 1 · Nov 15 | 205 days | 100% |
| Hard freeze (28°F) | Mar 13 · Mar 29 · Apr 9 | Oct 28 · Nov 12 · Dec 1 | 231 days | 100% |
Planting calendar for Harrisburg
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 | Mar 9 – May 15 |
| Tomatoes | Transplant outdoors | Apr 25 – Jul 12 |
| Peppers | Start seeds indoors | Mar 9 – Apr 9 |
| Peppers | Transplant outdoors | May 9 – Jun 9 |
| Eggplant | Start seeds indoors | Mar 26 – Apr 24 |
| Eggplant | Transplant outdoors | May 9 – Jun 9 |
| Cucumbers | Sow outdoors | May 9 – Jul 22 |
| Summer squash | Sow outdoors | Apr 25 – Jun 9 |
| Winter squash & pumpkins | Sow outdoors | May 9 – Jun 9 |
| Snap beans | Sow outdoors | Apr 25 – Aug 14 |
| Sweet corn | Sow outdoors | Apr 25 – Jul 12 |
| Watermelon & cantaloupe | Sow outdoors | May 9 – Jun 9 |
| Okra | Sow outdoors | May 2 – May 25 |
| Peas | Sow outdoors (spring) | Mar 9 – Apr 24 |
| Potatoes | Plant outdoors (spring) | Mar 9 – May 9 |
| Onions | Start seeds indoors (spring) | Jan 26 – Feb 22 |
| Onions | Transplant outdoors (spring) | Mar 26 – Apr 24 |
| Broccoli | Start seeds indoors (spring) | Feb 19 – Mar 25 |
| Broccoli | Transplant outdoors (spring) | Mar 26 – Apr 24 |
| Broccoli | Start seeds indoors (fall) | Jul 2 – Jul 12 |
| Broccoli | Transplant outdoors (fall) | Aug 1 – Aug 12 |
| Cabbage | Start seeds indoors (spring) | Feb 9 – Mar 9 |
| Cabbage | Transplant outdoors (spring) | Mar 9 – Apr 9 |
| Cabbage | Start seeds indoors (fall) | Jun 22 – Jul 22 |
| Cabbage | Transplant outdoors (fall) | Jul 22 – Aug 22 |
| Leaf lettuce | Sow outdoors (spring) | Mar 9 – May 25 |
| Leaf lettuce | Sow outdoors (fall) | Jul 22 – Sep 7 |
| Spinach | Sow outdoors (spring) | Mar 2 – Apr 15 |
| Spinach | Sow outdoors (fall) | Aug 8 – Sep 12 |
| Radishes | Sow outdoors (spring) | Mar 9 – Apr 29 |
| Radishes | Sow outdoors (fall) | Jul 22 – Sep 22 |
| Kale | Sow outdoors (spring) | Mar 26 – Apr 15 |
| Kale | Sow outdoors (fall) | Jul 15 – Aug 22 |
| Carrots | Sow outdoors (spring) | Apr 9 – May 25 |
| Carrots | Sow outdoors (fall) | Jun 22 – Aug 7 |
| Garlic | Plant outdoors (fall) | Oct 22 – Nov 22 |
Where these dates come from
ZIP code 17127 is matched to the NOAA station Harrisburg Cptl Cy Ap, PA, 5.5 km away, at 340 ft elevation (12 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Harrisburg Cptl Cy Ap, PA (used) | 340 ft | Apr 9 | Nov 1 |
| Harrisburg 1 Ne, PA | 420 ft | Apr 15 | Oct 23 |
| Middletown Harrisburg Intl Ap, PA | 312 ft | Apr 9 | Nov 2 |
| Dehart Dam, PA | 537 ft | May 1 | Oct 16 |
Frost dates near Harrisburg
- Harrisburg, PA 17129 · last Apr 9, first Nov 1
- Lemoyne, PA 17043 · last Apr 15, first Oct 23
- Camp Hill, PA 17012 · last Apr 15, first Oct 23
- New Cumberland, PA 17070 · last Apr 9, first Nov 1
- Enola, PA 17025 · last Apr 15, first Oct 23
- Summerdale, PA 17093 · last Apr 15, first Oct 23
- Highspire, PA 17034 · last Apr 9, first Nov 2
- Marysville, PA 17053 · last Apr 15, first Oct 23
Frequently asked questions
- When is the last frost in Harrisburg, PA?
- For ZIP code 17127, the average last spring frost (32°F) is April 9, based on NOAA 1991-2020 climate normals for the Harrisburg Cptl Cy Ap, PA weather station. There is a 1-in-10 chance of a frost after April 25.
- When is the first frost in Harrisburg, PA?
- The average first fall frost (32°F) is November 1. There is a 1-in-10 chance of frost by October 16, so tender plants are at risk from that point on.
- How long is the growing season in 17127?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 205 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.