Frost dates for 55785Swatara, MN
The average last spring frost in Swatara is May 7 and the average first fall frost is October 3, giving a typical growing season of about 148 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 7
- Average first fall frost
- Oct 3
- Growing season
- 148 days
Safer after May 21 (1-in-10 risk)
Possible by Sep 20 (1-in-10 risk)
Last frost typically in 186 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 5 · May 19 · Jun 1 | Sep 11 · Sep 24 · Oct 6 | 128 days | 100% |
| Frost / freeze (32°F) | Apr 26 · May 7 · May 21 | Sep 20 · Oct 3 · Oct 17 | 148 days | 100% |
| Hard freeze (28°F) | Apr 16 · Apr 29 · May 10 | Sep 30 · Oct 13 · Oct 26 | 167 days | 100% |
Planting calendar for Swatara
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 6 – Jun 12 |
| Tomatoes | Transplant outdoors | May 23 – Jun 13 |
| Peppers | Start seeds indoors | Apr 6 – May 7 |
| Peppers | Transplant outdoors | Jun 6 – Jul 7 |
| Eggplant | Start seeds indoors | Apr 23 – May 22 |
| Eggplant | Transplant outdoors | Jun 6 – Jul 7 |
| Cucumbers | Sow outdoors | Jun 6 – Jun 23 |
| Summer squash | Sow outdoors | May 23 – Jul 7 |
| Winter squash & pumpkins | Sow outdoors | Jun 6 – Jul 7 |
| Snap beans | Sow outdoors | May 23 – Jul 16 |
| Sweet corn | Sow outdoors | May 23 – Jun 13 |
| Watermelon & cantaloupe | Sow outdoors | Jun 6 – Jul 7 |
| Okra | Sow outdoors | May 30 – Jun 22 |
| Peas | Sow outdoors (spring) | Apr 6 – May 22 |
| Potatoes | Plant outdoors (spring) | Apr 6 – Jun 6 |
| Onions | Start seeds indoors (spring) | Feb 23 – Mar 22 |
| Onions | Transplant outdoors (spring) | Apr 23 – May 22 |
| Broccoli | Start seeds indoors (spring) | Mar 19 – Apr 22 |
| Broccoli | Transplant outdoors (spring) | Apr 23 – May 22 |
| Broccoli | Start seeds indoors (fall) | Jun 3 – Jun 13 |
| Broccoli | Transplant outdoors (fall) | Jul 3 – Jul 14 |
| Cabbage | Start seeds indoors (spring) | Mar 9 – Apr 6 |
| Cabbage | Transplant outdoors (spring) | Apr 6 – May 7 |
| Cabbage | Start seeds indoors (fall) | May 24 – Jun 23 |
| Cabbage | Transplant outdoors (fall) | Jun 23 – Jul 24 |
| Leaf lettuce | Sow outdoors (spring) | Apr 6 – Jun 22 |
| Leaf lettuce | Sow outdoors (fall) | Jun 23 – Aug 9 |
| Spinach | Sow outdoors (spring) | Mar 30 – May 13 |
| Spinach | Sow outdoors (fall) | Jul 10 – Aug 14 |
| Radishes | Sow outdoors (spring) | Apr 6 – May 27 |
| Radishes | Sow outdoors (fall) | Jun 23 – Aug 24 |
| Kale | Sow outdoors (spring) | Apr 23 – May 13 |
| Kale | Sow outdoors (fall) | Jun 16 – Jul 24 |
| Carrots | Sow outdoors (spring) | May 7 – Jun 22 |
| Carrots | Sow outdoors (fall) | May 24 – Jul 9 |
| Garlic | Plant outdoors (fall) | Sep 23 – Oct 24 |
Where these dates come from
ZIP code 55785 is matched to the NOAA station Sandy Lake Dam Libby, MN, 35.3 km away, at 1,234 ft elevation (124 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Sandy Lake Dam Libby, MN (used) | 1,234 ft | May 7 | Oct 3 |
| Pokegama Dam, MN | 1,280 ft | May 16 | Oct 1 |
| Pine Rvr Dam, MN | 1,250 ft | May 6 | Oct 7 |
| Grand Rpds Forest Lab, MN | 1,310 ft | May 17 | Sep 24 |
Frost dates near Swatara
- Hill City, MN 55748 · last May 17, first Sep 24
- Outing, MN 56662 · last May 6, first Oct 7
- Remer, MN 56672 · last May 8, first Oct 1
- Emily, MN 56447 · last May 6, first Oct 7
- Palisade, MN 56469 · last May 16, first Sep 28
- Fifty Lakes, MN 56448 · last May 6, first Oct 7
- Jacobson, MN 55752 · last May 7, first Oct 3
- Longville, MN 56655 · last May 5, first Oct 5
Frequently asked questions
- When is the last frost in Swatara, MN?
- For ZIP code 55785, the average last spring frost (32°F) is May 7, based on NOAA 1991-2020 climate normals for the Sandy Lake Dam Libby, MN weather station. There is a 1-in-10 chance of a frost after May 21.
- When is the first frost in Swatara, MN?
- The average first fall frost (32°F) is October 3. There is a 1-in-10 chance of frost by September 20, so tender plants are at risk from that point on.
- How long is the growing season in 55785?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 148 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.