Frost dates for 15857Saint Marys, PA
The average last spring frost in Saint Marys is May 14 and the average first fall frost is October 6, giving a typical growing season of about 143 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 14
- Average first fall frost
- Oct 6
- Growing season
- 143 days
Safer after May 29 (1-in-10 risk)
Possible by Sep 24 (1-in-10 risk)
Last frost typically in 192 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) | May 11 · May 27 · Jun 8 | Sep 12 · Sep 27 · Oct 8 | 121 days | 100% |
| Frost / freeze (32°F) | Apr 28 · May 14 · May 29 | Sep 24 · Oct 6 · Oct 20 | 143 days | 100% |
| Hard freeze (28°F) | Apr 18 · May 3 · May 19 | Oct 2 · Oct 18 · Nov 3 | 168 days | 100% |
Planting calendar for Saint Marys
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 | Apr 13 – Jun 19 |
| Tomatoes | Transplant outdoors | May 30 – Jun 16 |
| Peppers | Start seeds indoors | Apr 13 – May 14 |
| Peppers | Transplant outdoors | Jun 13 – Jul 14 |
| Eggplant | Start seeds indoors | Apr 30 – May 29 |
| Eggplant | Transplant outdoors | Jun 13 – Jul 14 |
| Cucumbers | Sow outdoors | Jun 13 – Jun 26 |
| Summer squash | Sow outdoors | May 30 – Jul 14 |
| Winter squash & pumpkins | Sow outdoors | Jun 13 – Jul 14 |
| Snap beans | Sow outdoors | May 30 – Jul 19 |
| Sweet corn | Sow outdoors | May 30 – Jun 16 |
| Watermelon & cantaloupe | Sow outdoors | Jun 13 – Jul 14 |
| Okra | Sow outdoors | Jun 6 – Jun 29 |
| Peas | Sow outdoors (spring) | Apr 13 – May 29 |
| Potatoes | Plant outdoors (spring) | Apr 13 – Jun 13 |
| Onions | Start seeds indoors (spring) | Mar 2 – Mar 29 |
| Onions | Transplant outdoors (spring) | Apr 30 – May 29 |
| Broccoli | Start seeds indoors (spring) | Mar 26 – Apr 29 |
| Broccoli | Transplant outdoors (spring) | Apr 30 – May 29 |
| Broccoli | Start seeds indoors (fall) | Jun 6 – Jun 16 |
| Broccoli | Transplant outdoors (fall) | Jul 6 – Jul 17 |
| Cabbage | Start seeds indoors (spring) | Mar 16 – Apr 13 |
| Cabbage | Transplant outdoors (spring) | Apr 13 – May 14 |
| Cabbage | Start seeds indoors (fall) | May 27 – Jun 26 |
| Cabbage | Transplant outdoors (fall) | Jun 26 – Jul 27 |
| Leaf lettuce | Sow outdoors (spring) | Apr 13 – Jun 29 |
| Leaf lettuce | Sow outdoors (fall) | Jun 26 – Aug 12 |
| Spinach | Sow outdoors (spring) | Apr 6 – May 20 |
| Spinach | Sow outdoors (fall) | Jul 13 – Aug 17 |
| Radishes | Sow outdoors (spring) | Apr 13 – Jun 3 |
| Radishes | Sow outdoors (fall) | Jun 26 – Aug 27 |
| Kale | Sow outdoors (spring) | Apr 30 – May 20 |
| Kale | Sow outdoors (fall) | Jun 19 – Jul 27 |
| Carrots | Sow outdoors (spring) | May 14 – Jun 29 |
| Carrots | Sow outdoors (fall) | May 27 – Jul 12 |
| Garlic | Plant outdoors (fall) | Sep 26 – Oct 27 |
Where these dates come from
ZIP code 15857 is matched to the NOAA station Glen Hazel 2 Ne Dam, PA, 15.2 km away, at 1,720 ft elevation (27 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Glen Hazel 2 Ne Dam, PA (used) | 1,720 ft | May 14 | Oct 6 |
| Ridgway, PA | 1,360 ft | May 13 | Oct 11 |
| Emporium, PA | 1,040 ft | May 7 | Oct 15 |
| Clermont 1 Nw, PA | 2,080 ft | May 15 | Oct 3 |
Frost dates near Saint Marys
- Kersey, PA 15846 · last May 14, first Oct 6
- Dagus Mines, PA 15831 · last May 14, first Oct 6
- De Young, PA 16728 · last May 13, first Oct 11
- Johnsonburg, PA 15845 · last May 13, first Oct 11
- Byrnedale, PA 15827 · last May 13, first Oct 11
- Ridgway, PA 15853 · last May 6, first Oct 14
- Brandy Camp, PA 15822 · last May 13, first Oct 11
- Weedville, PA 15868 · last May 13, first Oct 11
Frequently asked questions
- When is the last frost in Saint Marys, PA?
- For ZIP code 15857, the average last spring frost (32°F) is May 14, based on NOAA 1991-2020 climate normals for the Glen Hazel 2 Ne Dam, PA weather station. There is a 1-in-10 chance of a frost after May 29.
- When is the first frost in Saint Marys, PA?
- The average first fall frost (32°F) is October 6. There is a 1-in-10 chance of frost by September 24, so tender plants are at risk from that point on.
- How long is the growing season in 15857?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 143 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.