Frost dates for 16422Harmonsburg, PA
The average last spring frost in Harmonsburg is April 30 and the average first fall frost is October 23, giving a typical growing season of about 177 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 30
- Average first fall frost
- Oct 23
- Growing season
- 177 days
Safer after May 17 (1-in-10 risk)
Possible by Oct 6 (1-in-10 risk)
Last frost typically in 178 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 26 · May 11 · May 26 | Sep 27 · Oct 10 · Oct 25 | 151 days | 100% |
| Frost / freeze (32°F) | Apr 16 · Apr 30 · May 17 | Oct 6 · Oct 23 · Nov 6 | 177 days | 100% |
| Hard freeze (28°F) | Apr 3 · Apr 18 · May 3 | Oct 23 · Nov 5 · Nov 20 | 201 days | 100% |
Planting calendar for Harmonsburg
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 30 – Jun 5 |
| Tomatoes | Transplant outdoors | May 16 – Jul 3 |
| Peppers | Start seeds indoors | Mar 30 – Apr 30 |
| Peppers | Transplant outdoors | May 30 – Jun 30 |
| Eggplant | Start seeds indoors | Apr 16 – May 15 |
| Eggplant | Transplant outdoors | May 30 – Jun 30 |
| Cucumbers | Sow outdoors | May 30 – Jul 13 |
| Summer squash | Sow outdoors | May 16 – Jun 30 |
| Winter squash & pumpkins | Sow outdoors | May 30 – Jun 30 |
| Snap beans | Sow outdoors | May 16 – Aug 5 |
| Sweet corn | Sow outdoors | May 16 – Jul 3 |
| Watermelon & cantaloupe | Sow outdoors | May 30 – Jun 30 |
| Okra | Sow outdoors | May 23 – Jun 15 |
| Peas | Sow outdoors (spring) | Mar 30 – May 15 |
| Potatoes | Plant outdoors (spring) | Mar 30 – May 30 |
| Onions | Start seeds indoors (spring) | Feb 16 – Mar 15 |
| Onions | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (spring) | Mar 12 – Apr 15 |
| Broccoli | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (fall) | Jun 23 – Jul 3 |
| Broccoli | Transplant outdoors (fall) | Jul 23 – Aug 3 |
| Cabbage | Start seeds indoors (spring) | Mar 2 – Mar 30 |
| Cabbage | Transplant outdoors (spring) | Mar 30 – Apr 30 |
| Cabbage | Start seeds indoors (fall) | Jun 13 – Jul 13 |
| Cabbage | Transplant outdoors (fall) | Jul 13 – Aug 13 |
| Leaf lettuce | Sow outdoors (spring) | Mar 30 – Jun 15 |
| Leaf lettuce | Sow outdoors (fall) | Jul 13 – Aug 29 |
| Spinach | Sow outdoors (spring) | Mar 23 – May 6 |
| Spinach | Sow outdoors (fall) | Jul 30 – Sep 3 |
| Radishes | Sow outdoors (spring) | Mar 30 – May 20 |
| Radishes | Sow outdoors (fall) | Jul 13 – Sep 13 |
| Kale | Sow outdoors (spring) | Apr 16 – May 6 |
| Kale | Sow outdoors (fall) | Jul 6 – Aug 13 |
| Carrots | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Carrots | Sow outdoors (fall) | Jun 13 – Jul 29 |
| Garlic | Plant outdoors (fall) | Oct 13 – Nov 13 |
Where these dates come from
ZIP code 16422 is matched to the NOAA station Linesville 1 S, PA, 9.1 km away, at 1,030 ft elevation (92 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Linesville 1 S, PA (used) | 1,030 ft | Apr 30 | Oct 23 |
| Port Meadville Ap, PA | 1,400 ft | Apr 30 | Oct 23 |
| Springboro 3 Wnw, PA | 1,005 ft | May 8 | Oct 16 |
| Jamestown 2 Nw, PA | 1,040 ft | May 4 | Oct 14 |
Frost dates near Harmonsburg
- Conneaut Lake, PA 16316 · last Apr 30, first Oct 23
- Conneautville, PA 16406 · last May 8, first Oct 16
- Linesville, PA 16424 · last Apr 30, first Oct 23
- Meadville, PA 16388 · last Apr 30, first Oct 23
- Hartstown, PA 16131 · last May 4, first Oct 14
- Atlantic, PA 16111 · last Apr 30, first Oct 23
- Saegertown, PA 16433 · last Apr 30, first Oct 23
- Springboro, PA 16435 · last May 8, first Oct 16
Frequently asked questions
- When is the last frost in Harmonsburg, PA?
- For ZIP code 16422, the average last spring frost (32°F) is April 30, based on NOAA 1991-2020 climate normals for the Linesville 1 S, PA weather station. There is a 1-in-10 chance of a frost after May 17.
- When is the first frost in Harmonsburg, PA?
- The average first fall frost (32°F) is October 23. There is a 1-in-10 chance of frost by October 6, so tender plants are at risk from that point on.
- How long is the growing season in 16422?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 177 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.