Frost dates for 59008Belfry, MT
The average last spring frost in Belfry is May 18 and the average first fall frost is September 22, giving a typical growing season of about 125 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 18
- Average first fall frost
- Sep 22
- Growing season
- 125 days
Safer after Jun 4 (1-in-10 risk)
Possible by Sep 8 (1-in-10 risk)
Last frost typically in 196 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 17 · Jun 1 · Jun 17 | Aug 31 · Sep 12 · Sep 25 | 100 days | 100% |
| Frost / freeze (32°F) | May 6 · May 18 · Jun 4 | Sep 8 · Sep 22 · Oct 4 | 125 days | 100% |
| Hard freeze (28°F) | Apr 27 · May 7 · May 20 | Sep 18 · Oct 1 · Oct 14 | 146 days | 100% |
Planting calendar for Belfry
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 17 – Jun 23 |
| Tomatoes | Transplant outdoors | Jun 3 – Jun 2 |
| Peppers | Start seeds indoors | Apr 17 – May 18 |
| Peppers | Transplant outdoors | Jun 17 – Jul 18 |
| Eggplant | Start seeds indoors | May 4 – Jun 2 |
| Eggplant | Transplant outdoors | Jun 17 – Jul 18 |
| Cucumbers | Sow outdoors | Jun 17 – Jun 12 |
| Summer squash | Sow outdoors | Jun 3 – Jul 18 |
| Winter squash & pumpkins | Sow outdoors | Jun 17 – Jul 18 |
| Snap beans | Sow outdoors | Jun 3 – Jul 5 |
| Sweet corn | Sow outdoors | Jun 3 – Jun 2 |
| Watermelon & cantaloupe | Sow outdoors | Jun 17 – Jul 18 |
| Okra | Sow outdoors | Jun 10 – Jul 3 |
| Peas | Sow outdoors (spring) | Apr 17 – Jun 2 |
| Potatoes | Plant outdoors (spring) | Apr 17 – Jun 17 |
| Onions | Start seeds indoors (spring) | Mar 6 – Apr 2 |
| Onions | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (spring) | Mar 30 – May 3 |
| Broccoli | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (fall) | May 23 – Jun 2 |
| Broccoli | Transplant outdoors (fall) | Jun 22 – Jul 3 |
| Cabbage | Start seeds indoors (spring) | Mar 20 – Apr 17 |
| Cabbage | Transplant outdoors (spring) | Apr 17 – May 18 |
| Cabbage | Start seeds indoors (fall) | May 13 – Jun 12 |
| Cabbage | Transplant outdoors (fall) | Jun 12 – Jul 13 |
| Leaf lettuce | Sow outdoors (spring) | Apr 17 – Jul 3 |
| Leaf lettuce | Sow outdoors (fall) | Jun 12 – Jul 29 |
| Spinach | Sow outdoors (spring) | Apr 10 – May 24 |
| Spinach | Sow outdoors (fall) | Jun 29 – Aug 3 |
| Radishes | Sow outdoors (spring) | Apr 17 – Jun 7 |
| Radishes | Sow outdoors (fall) | Jun 12 – Aug 13 |
| Kale | Sow outdoors (spring) | May 4 – May 24 |
| Kale | Sow outdoors (fall) | Jun 5 – Jul 13 |
| Carrots | Sow outdoors (spring) | May 18 – Jul 3 |
| Carrots | Sow outdoors (fall) | May 13 – Jun 28 |
| Garlic | Plant outdoors (fall) | Sep 12 – Oct 13 |
Where these dates come from
ZIP code 59008 is matched to the NOAA station Clark 3Ne, WY, 13.4 km away, at 4,117 ft elevation (151 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Clark 3Ne, WY (used) | 4,117 ft | May 18 | Sep 22 |
| Red Lodge, MT | 5,646 ft | Jun 3 | Sep 19 |
| Bridger 2 N, MT | 3,583 ft | May 14 | Sep 24 |
| Powell Fld Stn, WY | 4,372 ft | May 19 | Sep 20 |
Frost dates near Belfry
- Bearcreek, MT 59007 · last May 18, first Sep 22
- Red Lodge, MT 59068 · last Jun 3, first Sep 19
- Bridger, MT 59014 · last May 14, first Sep 24
- Roberts, MT 59070 · last May 29, first Sep 15
- Frannie, WY 82423 · last May 6, first Oct 1
- Deaver, WY 82421 · last May 6, first Oct 1
- Powell, WY 82435 · last May 19, first Sep 20
- Ralston, WY 82440 · last May 15, first Sep 25
Frequently asked questions
- When is the last frost in Belfry, MT?
- For ZIP code 59008, the average last spring frost (32°F) is May 18, based on NOAA 1991-2020 climate normals for the Clark 3Ne, WY weather station. There is a 1-in-10 chance of a frost after June 4.
- When is the first frost in Belfry, MT?
- The average first fall frost (32°F) is September 22. There is a 1-in-10 chance of frost by September 8, so tender plants are at risk from that point on.
- How long is the growing season in 59008?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 125 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.