Frost dates for 59301Miles City, MT
The average last spring frost in Miles City is May 8 and the average first fall frost is September 30, giving a typical growing season of about 144 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 8
- Average first fall frost
- Sep 30
- Growing season
- 144 days
Safer after May 21 (1-in-10 risk)
Possible by Sep 17 (1-in-10 risk)
Last frost typically in 186 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 7 · May 18 · May 31 | Sep 10 · Sep 23 · Oct 4 | 124 days | 100% |
| Frost / freeze (32°F) | Apr 26 · May 8 · May 21 | Sep 17 · Sep 30 · Oct 14 | 144 days | 100% |
| Hard freeze (28°F) | Apr 13 · Apr 29 · May 12 | Sep 25 · Oct 8 · Oct 23 | 163 days | 100% |
Planting calendar for Miles City
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 7 – Jun 13 |
| Tomatoes | Transplant outdoors | May 24 – Jun 10 |
| Peppers | Start seeds indoors | Apr 7 – May 8 |
| Peppers | Transplant outdoors | Jun 7 – Jul 8 |
| Eggplant | Start seeds indoors | Apr 24 – May 23 |
| Eggplant | Transplant outdoors | Jun 7 – Jul 8 |
| Cucumbers | Sow outdoors | Jun 7 – Jun 20 |
| Summer squash | Sow outdoors | May 24 – Jul 8 |
| Winter squash & pumpkins | Sow outdoors | Jun 7 – Jul 8 |
| Snap beans | Sow outdoors | May 24 – Jul 13 |
| Sweet corn | Sow outdoors | May 24 – Jun 10 |
| Watermelon & cantaloupe | Sow outdoors | Jun 7 – Jul 8 |
| Okra | Sow outdoors | May 31 – Jun 23 |
| Peas | Sow outdoors (spring) | Apr 7 – May 23 |
| Potatoes | Plant outdoors (spring) | Apr 7 – Jun 7 |
| Onions | Start seeds indoors (spring) | Feb 24 – Mar 23 |
| Onions | Transplant outdoors (spring) | Apr 24 – May 23 |
| Broccoli | Start seeds indoors (spring) | Mar 20 – Apr 23 |
| Broccoli | Transplant outdoors (spring) | Apr 24 – May 23 |
| Broccoli | Start seeds indoors (fall) | May 31 – Jun 10 |
| Broccoli | Transplant outdoors (fall) | Jun 30 – Jul 11 |
| Cabbage | Start seeds indoors (spring) | Mar 10 – Apr 7 |
| Cabbage | Transplant outdoors (spring) | Apr 7 – May 8 |
| Cabbage | Start seeds indoors (fall) | May 21 – Jun 20 |
| Cabbage | Transplant outdoors (fall) | Jun 20 – Jul 21 |
| Leaf lettuce | Sow outdoors (spring) | Apr 7 – Jun 23 |
| Leaf lettuce | Sow outdoors (fall) | Jun 20 – Aug 6 |
| Spinach | Sow outdoors (spring) | Mar 31 – May 14 |
| Spinach | Sow outdoors (fall) | Jul 7 – Aug 11 |
| Radishes | Sow outdoors (spring) | Apr 7 – May 28 |
| Radishes | Sow outdoors (fall) | Jun 20 – Aug 21 |
| Kale | Sow outdoors (spring) | Apr 24 – May 14 |
| Kale | Sow outdoors (fall) | Jun 13 – Jul 21 |
| Carrots | Sow outdoors (spring) | May 8 – Jun 23 |
| Carrots | Sow outdoors (fall) | May 21 – Jul 6 |
| Garlic | Plant outdoors (fall) | Sep 20 – Oct 21 |
Where these dates come from
ZIP code 59301 is matched to the NOAA station Miles City F Wiley Fld, MT, 4.3 km away, at 2,624 ft elevation (262 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Miles City F Wiley Fld, MT (used) | 2,624 ft | May 8 | Sep 30 |
| Mizpah 4 Nnw, MT | 2,480 ft | May 22 | Sep 15 |
| Rock Springs, MT | 3,024 ft | May 15 | Sep 25 |
| Terry, MT | 2,250 ft | May 12 | Sep 28 |
Frost dates near Miles City
- Kinsey, MT 59338 · last May 8, first Sep 30
- Hathaway, MT 59333 · last May 8, first Sep 30
- Rosebud, MT 59347 · last May 9, first Sep 29
- Angela, MT 59312 · last May 15, first Sep 25
- Ismay, MT 59336 · last May 22, first Sep 15
- Terry, MT 59349 · last May 12, first Sep 28
- Volborg, MT 59351 · last May 16, first Sep 28
- Forsyth, MT 59327 · last May 9, first Sep 29
Frequently asked questions
- When is the last frost in Miles City, MT?
- For ZIP code 59301, the average last spring frost (32°F) is May 8, based on NOAA 1991-2020 climate normals for the Miles City F Wiley Fld, MT weather station. There is a 1-in-10 chance of a frost after May 21.
- When is the first frost in Miles City, MT?
- The average first fall frost (32°F) is September 30. There is a 1-in-10 chance of frost by September 17, so tender plants are at risk from that point on.
- How long is the growing season in 59301?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 144 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.