Frost dates for 59751Silver Star, MT
The average last spring frost in Silver Star is June 8 and the average first fall frost is September 2, giving a typical growing season of about 82 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 8
- Average first fall frost
- Sep 2
- Growing season
- 82 days
Safer after Jul 1 (1-in-10 risk)
Possible by Aug 16 (1-in-10 risk)
Last frost typically in 217 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) | — | — | 46 days | 100% |
| Frost / freeze (32°F) | May 22 · Jun 8 · Jul 1 | Aug 16 · Sep 2 · Sep 15 | 82 days | 100% |
| Hard freeze (28°F) | May 7 · May 20 · Jun 6 | Aug 31 · Sep 15 · Oct 1 | 116 days | 100% |
Where these dates come from
ZIP code 59751 is matched to the NOAA station Twin Bridges, MT, 17.9 km away, at 4,625 ft elevation (127 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Twin Bridges, MT (used) | 4,625 ft | Jun 8 | Sep 2 |
| Butte Bert Mooney Ap, MT | 5,506 ft | Jun 13 | Sep 5 |
| Laurin 2Ne, MT | 5,198 ft | May 24 | Sep 22 |
| Divide, MT | 5,350 ft | Jun 10 | Sep 7 |
Frost dates near Silver Star
- Twin Bridges, MT 59754 · last Jun 8, first Sep 2
- Whitehall, MT 59759 · last Jun 8, first Sep 2
- Pony, MT 59747 · last Jun 4, first Sep 18
- Sheridan, MT 59749 · last May 24, first Sep 22
- Harrison, MT 59735 · last Apr 30, first Oct 10
- Melrose, MT 59743 · last Jun 10, first Sep 7
- Butte, MT 59702 · last Jun 13, first Sep 5
- Glen, MT 59732 · last —, first —
Frequently asked questions
- When is the last frost in Silver Star, MT?
- For ZIP code 59751, the average last spring frost (32°F) is June 8, based on NOAA 1991-2020 climate normals for the Twin Bridges, MT weather station. There is a 1-in-10 chance of a frost after July 1.
- When is the first frost in Silver Star, MT?
- The average first fall frost (32°F) is September 2. There is a 1-in-10 chance of frost by August 16, so tender plants are at risk from that point on.
- How long is the growing season in 59751?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 82 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.