Frost dates for 59460Loma, MT
The average last spring frost in Loma is May 20 and the average first fall frost is September 19, giving a typical growing season of about 120 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 20
- Average first fall frost
- Sep 19
- Growing season
- 120 days
Safer after Jun 3 (1-in-10 risk)
Possible by Sep 4 (1-in-10 risk)
Last frost typically in 198 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 20 · Jun 2 · Jun 21 | Aug 22 · Sep 7 · Sep 21 | 94 days | 100% |
| Frost / freeze (32°F) | May 8 · May 20 · Jun 3 | Sep 4 · Sep 19 · Oct 2 | 120 days | 100% |
| Hard freeze (28°F) | Apr 25 · May 9 · May 21 | Sep 16 · Sep 29 · Oct 11 | 143 days | 100% |
Planting calendar for Loma
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 19 – Jun 25 |
| Tomatoes | Transplant outdoors | Jun 5 – May 30 |
| Peppers | Start seeds indoors | Apr 19 – May 20 |
| Peppers | Transplant outdoors | Jun 19 – Jul 20 |
| Eggplant | Start seeds indoors | May 6 – Jun 4 |
| Eggplant | Transplant outdoors | Jun 19 – Jul 20 |
| Cucumbers | Sow outdoors | Jun 19 – Jun 9 |
| Summer squash | Sow outdoors | Jun 5 – Jul 20 |
| Winter squash & pumpkins | Sow outdoors | Jun 19 – Jul 20 |
| Snap beans | Sow outdoors | Jun 5 – Jul 2 |
| Sweet corn | Sow outdoors | Jun 5 – May 30 |
| Watermelon & cantaloupe | Sow outdoors | Jun 19 – Jul 20 |
| Okra | Sow outdoors | Jun 12 – Jul 5 |
| Peas | Sow outdoors (spring) | Apr 19 – Jun 4 |
| Potatoes | Plant outdoors (spring) | Apr 19 – Jun 19 |
| Onions | Start seeds indoors (spring) | Mar 8 – Apr 4 |
| Onions | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (spring) | Apr 1 – May 5 |
| Broccoli | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (fall) | May 20 – May 30 |
| Broccoli | Transplant outdoors (fall) | Jun 19 – Jun 30 |
| Cabbage | Start seeds indoors (spring) | Mar 22 – Apr 19 |
| Cabbage | Transplant outdoors (spring) | Apr 19 – May 20 |
| Cabbage | Start seeds indoors (fall) | May 10 – Jun 9 |
| Cabbage | Transplant outdoors (fall) | Jun 9 – Jul 10 |
| Leaf lettuce | Sow outdoors (spring) | Apr 19 – Jul 5 |
| Leaf lettuce | Sow outdoors (fall) | Jun 9 – Jul 26 |
| Spinach | Sow outdoors (spring) | Apr 12 – May 26 |
| Spinach | Sow outdoors (fall) | Jun 26 – Jul 31 |
| Radishes | Sow outdoors (spring) | Apr 19 – Jun 9 |
| Radishes | Sow outdoors (fall) | Jun 9 – Aug 10 |
| Kale | Sow outdoors (spring) | May 6 – May 26 |
| Kale | Sow outdoors (fall) | Jun 2 – Jul 10 |
| Carrots | Sow outdoors (spring) | May 20 – Jul 5 |
| Carrots | Sow outdoors (fall) | May 10 – Jun 25 |
| Garlic | Plant outdoors (fall) | Sep 9 – Oct 10 |
Where these dates come from
ZIP code 59460 is matched to the NOAA station Loma, MT, 2 km away, at 2,578 ft elevation (198 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Loma, MT (used) | 2,578 ft | May 20 | Sep 19 |
| Ft Benton, MT | 2,649 ft | May 15 | Sep 22 |
| Rudyard 19S, MT | 2,878 ft | May 23 | Sep 19 |
| Highwood 7 Ne, MT | 3,600 ft | May 7 | Oct 2 |
Frost dates near Loma
- Fort Benton, MT 59442 · last May 20, first Sep 19
- Big Sandy, MT 59520 · last May 17, first Sep 25
- Carter, MT 59420 · last May 23, first Sep 23
- Geraldine, MT 59446 · last May 14, first Sep 26
- Highwood, MT 59450 · last May 7, first Oct 2
- Floweree, MT 59440 · last May 23, first Sep 23
- Box Elder, MT 59521 · last May 17, first Sep 25
- Chester, MT 59522 · last May 24, first Sep 17
Frequently asked questions
- When is the last frost in Loma, MT?
- For ZIP code 59460, the average last spring frost (32°F) is May 20, based on NOAA 1991-2020 climate normals for the Loma, MT weather station. There is a 1-in-10 chance of a frost after June 3.
- When is the first frost in Loma, MT?
- The average first fall frost (32°F) is September 19. There is a 1-in-10 chance of frost by September 4, so tender plants are at risk from that point on.
- How long is the growing season in 59460?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 120 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.