Frost dates for 59016Busby, MT
The average last spring frost in Busby is May 23 and the average first fall frost is September 15, giving a typical growing season of about 113 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 23
- Average first fall frost
- Sep 15
- Growing season
- 113 days
Safer after Jun 7 (1-in-10 risk)
Possible by Sep 1 (1-in-10 risk)
Last frost typically in 201 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 24 · Jun 8 · Jul 2 | Aug 20 · Sep 4 · Sep 18 | 86 days | 100% |
| Frost / freeze (32°F) | May 12 · May 23 · Jun 7 | Sep 1 · Sep 15 · Oct 1 | 113 days | 100% |
| Hard freeze (28°F) | Apr 30 · May 11 · May 24 | Sep 11 · Sep 27 · Oct 11 | 136 days | 100% |
Planting calendar for Busby
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 22 – Jun 28 |
| Tomatoes | Transplant outdoors | Jun 8 – May 26 |
| Peppers | Start seeds indoors | Apr 22 – May 23 |
| Peppers | Transplant outdoors | Jun 22 – Jul 23 |
| Eggplant | Start seeds indoors | May 9 – Jun 7 |
| Eggplant | Transplant outdoors | Jun 22 – Jul 23 |
| Cucumbers | Sow outdoors | Jun 22 – Jun 5 |
| Summer squash | Sow outdoors | Jun 8 – Jul 23 |
| Winter squash & pumpkins | Sow outdoors | Jun 22 – Jul 23 |
| Snap beans | Sow outdoors | Jun 8 – Jun 28 |
| Sweet corn | Sow outdoors | Jun 8 – May 26 |
| Watermelon & cantaloupe | Sow outdoors | Jun 22 – Jul 23 |
| Okra | Sow outdoors | Jun 15 – Jul 8 |
| Peas | Sow outdoors (spring) | Apr 22 – Jun 7 |
| Potatoes | Plant outdoors (spring) | Apr 22 – Jun 22 |
| Onions | Start seeds indoors (spring) | Mar 11 – Apr 7 |
| Onions | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (spring) | Apr 4 – May 8 |
| Broccoli | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (fall) | May 16 – May 26 |
| Broccoli | Transplant outdoors (fall) | Jun 15 – Jun 26 |
| Cabbage | Start seeds indoors (spring) | Mar 25 – Apr 22 |
| Cabbage | Transplant outdoors (spring) | Apr 22 – May 23 |
| Cabbage | Start seeds indoors (fall) | May 6 – Jun 5 |
| Cabbage | Transplant outdoors (fall) | Jun 5 – Jul 6 |
| Leaf lettuce | Sow outdoors (spring) | Apr 22 – Jul 8 |
| Leaf lettuce | Sow outdoors (fall) | Jun 5 – Jul 22 |
| Spinach | Sow outdoors (spring) | Apr 15 – May 29 |
| Spinach | Sow outdoors (fall) | Jun 22 – Jul 27 |
| Radishes | Sow outdoors (spring) | Apr 22 – Jun 12 |
| Radishes | Sow outdoors (fall) | Jun 5 – Aug 6 |
| Kale | Sow outdoors (spring) | May 9 – May 29 |
| Kale | Sow outdoors (fall) | May 29 – Jul 6 |
| Carrots | Sow outdoors (spring) | May 23 – Jul 8 |
| Carrots | Sow outdoors (fall) | May 6 – Jun 21 |
| Garlic | Plant outdoors (fall) | Sep 5 – Oct 6 |
Where these dates come from
ZIP code 59016 is matched to the NOAA station Busby, MT, 7 km away, at 3,430 ft elevation (172 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Busby, MT (used) | 3,430 ft | May 23 | Sep 15 |
| Colstrip, MT | 3,218 ft | May 15 | Sep 30 |
| Hysham 25 Sse, MT | 3,100 ft | May 26 | Sep 16 |
| Brandenberg, MT | 2,770 ft | May 18 | Sep 22 |
Frost dates near Busby
- Lame Deer, MT 59043 · last May 23, first Sep 15
- Birney, MT 59012 · last May 23, first Sep 15
- Decker, MT 59025 · last May 21, first Sep 23
- Colstrip, MT 59323 · last May 15, first Sep 30
- Ashland, MT 59003 · last May 18, first Sep 22
- Lodge Grass, MT 59050 · last May 23, first Sep 15
- Garryowen, MT 59031 · last May 7, first Oct 5
- Crow Agency, MT 59022 · last May 13, first Sep 29
Frequently asked questions
- When is the last frost in Busby, MT?
- For ZIP code 59016, the average last spring frost (32°F) is May 23, based on NOAA 1991-2020 climate normals for the Busby, MT weather station. There is a 1-in-10 chance of a frost after June 7.
- When is the first frost in Busby, MT?
- The average first fall frost (32°F) is September 15. There is a 1-in-10 chance of frost by September 1, so tender plants are at risk from that point on.
- How long is the growing season in 59016?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 113 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.