Frost dates for 59412Belt, MT
The average last spring frost in Belt is May 22 and the average first fall frost is September 23, giving a typical growing season of about 123 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 22
- Average first fall frost
- Sep 23
- Growing season
- 123 days
Safer after Jun 9 (1-in-10 risk)
Possible by Sep 7 (1-in-10 risk)
Last frost typically in 200 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 23 · Jun 9 · Jul 3 | Aug 27 · Sep 12 · Sep 25 | 92 days | 100% |
| Frost / freeze (32°F) | May 7 · May 22 · Jun 9 | Sep 7 · Sep 23 · Oct 6 | 123 days | 100% |
| Hard freeze (28°F) | Apr 23 · May 7 · May 22 | Sep 20 · Oct 2 · Oct 18 | 147 days | 100% |
Planting calendar for Belt
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 21 – Jun 27 |
| Tomatoes | Transplant outdoors | Jun 7 – Jun 3 |
| Peppers | Start seeds indoors | Apr 21 – May 22 |
| Peppers | Transplant outdoors | Jun 21 – Jul 22 |
| Eggplant | Start seeds indoors | May 8 – Jun 6 |
| Eggplant | Transplant outdoors | Jun 21 – Jul 22 |
| Cucumbers | Sow outdoors | Jun 21 – Jun 13 |
| Summer squash | Sow outdoors | Jun 7 – Jul 22 |
| Winter squash & pumpkins | Sow outdoors | Jun 21 – Jul 22 |
| Snap beans | Sow outdoors | Jun 7 – Jul 6 |
| Sweet corn | Sow outdoors | Jun 7 – Jun 3 |
| Watermelon & cantaloupe | Sow outdoors | Jun 21 – Jul 22 |
| Okra | Sow outdoors | Jun 14 – Jul 7 |
| Peas | Sow outdoors (spring) | Apr 21 – Jun 6 |
| Potatoes | Plant outdoors (spring) | Apr 21 – Jun 21 |
| Onions | Start seeds indoors (spring) | Mar 10 – Apr 6 |
| Onions | Transplant outdoors (spring) | May 8 – Jun 6 |
| Broccoli | Start seeds indoors (spring) | Apr 3 – May 7 |
| Broccoli | Transplant outdoors (spring) | May 8 – Jun 6 |
| Broccoli | Start seeds indoors (fall) | May 24 – Jun 3 |
| Broccoli | Transplant outdoors (fall) | Jun 23 – Jul 4 |
| Cabbage | Start seeds indoors (spring) | Mar 24 – Apr 21 |
| Cabbage | Transplant outdoors (spring) | Apr 21 – May 22 |
| Cabbage | Start seeds indoors (fall) | May 14 – Jun 13 |
| Cabbage | Transplant outdoors (fall) | Jun 13 – Jul 14 |
| Leaf lettuce | Sow outdoors (spring) | Apr 21 – Jul 7 |
| Leaf lettuce | Sow outdoors (fall) | Jun 13 – Jul 30 |
| Spinach | Sow outdoors (spring) | Apr 14 – May 28 |
| Spinach | Sow outdoors (fall) | Jun 30 – Aug 4 |
| Radishes | Sow outdoors (spring) | Apr 21 – Jun 11 |
| Radishes | Sow outdoors (fall) | Jun 13 – Aug 14 |
| Kale | Sow outdoors (spring) | May 8 – May 28 |
| Kale | Sow outdoors (fall) | Jun 6 – Jul 14 |
| Carrots | Sow outdoors (spring) | May 22 – Jul 7 |
| Carrots | Sow outdoors (fall) | May 14 – Jun 29 |
| Garlic | Plant outdoors (fall) | Sep 13 – Oct 14 |
Where these dates come from
ZIP code 59412 is matched to the NOAA station Raynesford 2 Nnw, MT, 15.5 km away, at 4,215 ft elevation (350 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Raynesford 2 Nnw, MT (used) | 4,215 ft | May 22 | Sep 23 |
| Shonkin 7 S, MT | 4,300 ft | May 24 | Sep 21 |
| Great Falls 16St, MT | 3,505 ft | May 6 | Oct 1 |
| Highwood 7 Ne, MT | 3,600 ft | May 7 | Oct 2 |
Frost dates near Belt
- Stockett, MT 59480 · last May 22, first Sep 23
- Sand Coulee, MT 59472 · last May 19, first Sep 24
- Raynesford, MT 59469 · last May 22, first Sep 23
- Highwood, MT 59450 · last May 7, first Oct 2
- Great Falls, MT 59405 · last May 6, first Oct 1
- Black Eagle, MT 59414 · last May 19, first Sep 24
- Malmstrom Afb, MT 59402 · last May 19, first Sep 24
- Monarch, MT 59463 · last Jun 6, first Sep 12
Frequently asked questions
- When is the last frost in Belt, MT?
- For ZIP code 59412, the average last spring frost (32°F) is May 22, based on NOAA 1991-2020 climate normals for the Raynesford 2 Nnw, MT weather station. There is a 1-in-10 chance of a frost after June 9.
- When is the first frost in Belt, MT?
- The average first fall frost (32°F) is September 23. There is a 1-in-10 chance of frost by September 7, so tender plants are at risk from that point on.
- How long is the growing season in 59412?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 123 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.