Frost dates for 59071Roscoe, MT
The average last spring frost in Roscoe is June 3 and the average first fall frost is September 19, giving a typical growing season of about 106 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 3
- Average first fall frost
- Sep 19
- Growing season
- 106 days
Safer after Jun 18 (1-in-10 risk)
Possible by Aug 31 (1-in-10 risk)
Last frost typically in 219 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) | Jun 3 · Jun 19 · Jul 7 | Aug 14 · Sep 5 · Sep 22 | 77 days | 100% |
| Frost / freeze (32°F) | May 19 · Jun 3 · Jun 18 | Aug 31 · Sep 19 · Oct 3 | 106 days | 100% |
| Hard freeze (28°F) | May 1 · May 17 · Jun 4 | Sep 15 · Oct 1 · Oct 14 | 133 days | 100% |
Planting calendar for Roscoe
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 | May 3 – Jul 9 |
| Tomatoes | Transplant outdoors | Jun 19 – May 30 |
| Peppers | Start seeds indoors | May 3 – Jun 3 |
| Peppers | Transplant outdoors | Jul 3 – Aug 3 |
| Eggplant | Start seeds indoors | May 20 – Jun 18 |
| Eggplant | Transplant outdoors | Jul 3 – Aug 3 |
| Cucumbers | Sow outdoors | Jul 3 – Jun 9 |
| Summer squash | Sow outdoors | Jun 19 – Aug 3 |
| Winter squash & pumpkins | Sow outdoors | Jul 3 – Aug 3 |
| Snap beans | Sow outdoors | Jun 19 – Jul 2 |
| Sweet corn | Sow outdoors | Jun 19 – May 30 |
| Watermelon & cantaloupe | Sow outdoors | Jul 3 – Aug 3 |
| Okra | Sow outdoors | Jun 26 – Jul 19 |
| Peas | Sow outdoors (spring) | May 3 – Jun 18 |
| Potatoes | Plant outdoors (spring) | May 3 – Jul 3 |
| Onions | Start seeds indoors (spring) | Mar 22 – Apr 18 |
| Onions | Transplant outdoors (spring) | May 20 – Jun 18 |
| Broccoli | Start seeds indoors (spring) | Apr 15 – May 19 |
| Broccoli | Transplant outdoors (spring) | May 20 – Jun 18 |
| Broccoli | Start seeds indoors (fall) | May 20 – May 30 |
| Broccoli | Transplant outdoors (fall) | Jun 19 – Jun 30 |
| Cabbage | Start seeds indoors (spring) | Apr 5 – May 3 |
| Cabbage | Transplant outdoors (spring) | May 3 – Jun 3 |
| Cabbage | Start seeds indoors (fall) | May 10 – Jun 9 |
| Cabbage | Transplant outdoors (fall) | Jun 9 – Jul 10 |
| Leaf lettuce | Sow outdoors (spring) | May 3 – Jul 19 |
| Leaf lettuce | Sow outdoors (fall) | Jun 9 – Jul 26 |
| Spinach | Sow outdoors (spring) | Apr 26 – Jun 9 |
| Spinach | Sow outdoors (fall) | Jun 26 – Jul 31 |
| Radishes | Sow outdoors (spring) | May 3 – Jun 23 |
| Radishes | Sow outdoors (fall) | Jun 9 – Aug 10 |
| Kale | Sow outdoors (spring) | May 20 – Jun 9 |
| Kale | Sow outdoors (fall) | Jun 2 – Jul 10 |
| Carrots | Sow outdoors (spring) | Jun 3 – Jul 19 |
| Carrots | Sow outdoors (fall) | May 10 – Jun 25 |
| Garlic | Plant outdoors (fall) | Sep 9 – Oct 10 |
Where these dates come from
ZIP code 59071 is matched to the NOAA station Red Lodge, MT, 26.2 km away, at 5,646 ft elevation (144 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Red Lodge, MT (used) | 5,646 ft | Jun 3 | Sep 19 |
| Mystic Lake, MT | 6,544 ft | Jun 5 | Sep 14 |
| Nye #2, MT | 4,840 ft | Jun 1 | Sep 11 |
| Silver Gate, MT | 7,495 ft | — | — |
Frost dates near Roscoe
- Fishtail, MT 59028 · last Jun 3, first Sep 19
- Red Lodge, MT 59068 · last Jun 3, first Sep 19
- Nye, MT 59061 · last Jun 1, first Sep 11
- Absarokee, MT 59001 · last Jun 1, first Sep 11
- Roberts, MT 59070 · last May 29, first Sep 15
- Bearcreek, MT 59007 · last May 18, first Sep 22
- Cooke City, MT 59020 · last —, first —
- Silver Gate, MT 59081 · last —, first —
Frequently asked questions
- When is the last frost in Roscoe, MT?
- For ZIP code 59071, the average last spring frost (32°F) is June 3, based on NOAA 1991-2020 climate normals for the Red Lodge, MT weather station. There is a 1-in-10 chance of a frost after June 18.
- When is the first frost in Roscoe, MT?
- The average first fall frost (32°F) is September 19. There is a 1-in-10 chance of frost by August 31, so tender plants are at risk from that point on.
- How long is the growing season in 59071?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 106 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.