Frost dates for 17237Mont Alto, PA
The average last spring frost in Mont Alto is April 18 and the average first fall frost is October 25, giving a typical growing season of about 188 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 18
- Average first fall frost
- Oct 25
- Growing season
- 188 days
Safer after May 5 (1-in-10 risk)
Possible by Oct 10 (1-in-10 risk)
Last frost typically in 168 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 16 · Apr 30 · May 17 | Oct 1 · Oct 14 · Oct 28 | 165 days | 100% |
| Frost / freeze (32°F) | Apr 3 · Apr 18 · May 5 | Oct 10 · Oct 25 · Nov 8 | 188 days | 100% |
| Hard freeze (28°F) | Mar 21 · Apr 4 · Apr 21 | Oct 23 · Nov 6 · Nov 21 | 213 days | 100% |
Planting calendar for Mont Alto
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 18 – May 24 |
| Tomatoes | Transplant outdoors | May 4 – Jul 5 |
| Peppers | Start seeds indoors | Mar 18 – Apr 18 |
| Peppers | Transplant outdoors | May 18 – Jun 18 |
| Eggplant | Start seeds indoors | Apr 4 – May 3 |
| Eggplant | Transplant outdoors | May 18 – Jun 18 |
| Cucumbers | Sow outdoors | May 18 – Jul 15 |
| Summer squash | Sow outdoors | May 4 – Jun 18 |
| Winter squash & pumpkins | Sow outdoors | May 18 – Jun 18 |
| Snap beans | Sow outdoors | May 4 – Aug 7 |
| Sweet corn | Sow outdoors | May 4 – Jul 5 |
| Watermelon & cantaloupe | Sow outdoors | May 18 – Jun 18 |
| Okra | Sow outdoors | May 11 – Jun 3 |
| Peas | Sow outdoors (spring) | Mar 18 – May 3 |
| Potatoes | Plant outdoors (spring) | Mar 18 – May 18 |
| Onions | Start seeds indoors (spring) | Feb 4 – Mar 3 |
| Onions | Transplant outdoors (spring) | Apr 4 – May 3 |
| Broccoli | Start seeds indoors (spring) | Feb 28 – Apr 3 |
| Broccoli | Transplant outdoors (spring) | Apr 4 – May 3 |
| Broccoli | Start seeds indoors (fall) | Jun 25 – Jul 5 |
| Broccoli | Transplant outdoors (fall) | Jul 25 – Aug 5 |
| Cabbage | Start seeds indoors (spring) | Feb 18 – Mar 18 |
| Cabbage | Transplant outdoors (spring) | Mar 18 – Apr 18 |
| Cabbage | Start seeds indoors (fall) | Jun 15 – Jul 15 |
| Cabbage | Transplant outdoors (fall) | Jul 15 – Aug 15 |
| Leaf lettuce | Sow outdoors (spring) | Mar 18 – Jun 3 |
| Leaf lettuce | Sow outdoors (fall) | Jul 15 – Aug 31 |
| Spinach | Sow outdoors (spring) | Mar 11 – Apr 24 |
| Spinach | Sow outdoors (fall) | Aug 1 – Sep 5 |
| Radishes | Sow outdoors (spring) | Mar 18 – May 8 |
| Radishes | Sow outdoors (fall) | Jul 15 – Sep 15 |
| Kale | Sow outdoors (spring) | Apr 4 – Apr 24 |
| Kale | Sow outdoors (fall) | Jul 8 – Aug 15 |
| Carrots | Sow outdoors (spring) | Apr 18 – Jun 3 |
| Carrots | Sow outdoors (fall) | Jun 15 – Jul 31 |
| Garlic | Plant outdoors (fall) | Oct 15 – Nov 15 |
Where these dates come from
ZIP code 17237 is matched to the NOAA station Chambersburg 1 Ese, PA, 12.7 km away, at 640 ft elevation (239 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Chambersburg 1 Ese, PA (used) | 640 ft | Apr 18 | Oct 25 |
| S Mtn, PA | 1,520 ft | Apr 27 | Oct 20 |
| Cashtown 1S, PA | 710 ft | Apr 28 | Oct 17 |
| Smithsburg 2Nw, MD | 670 ft | Apr 25 | Oct 19 |
Frost dates near Mont Alto
- Quincy, PA 17247 · last Apr 7, first Nov 4
- South Mountain, PA 17261 · last Apr 27, first Oct 20
- Fayetteville, PA 17222 · last Apr 18, first Oct 25
- Waynesboro, PA 17268 · last Apr 7, first Nov 4
- Zullinger, PA 17272 · last Apr 7, first Nov 4
- Chambersburg, PA 17202 · last Apr 18, first Oct 25
- Rouzerville, PA 17250 · last Apr 7, first Nov 4
- Shady Grove, PA 17256 · last Apr 7, first Nov 4
Frequently asked questions
- When is the last frost in Mont Alto, PA?
- For ZIP code 17237, the average last spring frost (32°F) is April 18, based on NOAA 1991-2020 climate normals for the Chambersburg 1 Ese, PA weather station. There is a 1-in-10 chance of a frost after May 5.
- When is the first frost in Mont Alto, PA?
- The average first fall frost (32°F) is October 25. There is a 1-in-10 chance of frost by October 10, so tender plants are at risk from that point on.
- How long is the growing season in 17237?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 188 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.