Frost dates for 59486Valier, MT
The average last spring frost in Valier is May 17 and the average first fall frost is September 24, giving a typical growing season of about 129 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 17
- Average first fall frost
- Sep 24
- Growing season
- 129 days
Safer after May 31 (1-in-10 risk)
Possible by Sep 11 (1-in-10 risk)
Last frost typically in 202 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 18 · Jun 2 · Jun 25 | Aug 29 · Sep 13 · Sep 26 | 101 days | 100% |
| Frost / freeze (32°F) | May 3 · May 17 · May 31 | Sep 11 · Sep 24 · Oct 5 | 129 days | 100% |
| Hard freeze (28°F) | Apr 20 · May 4 · May 18 | Sep 22 · Oct 4 · Oct 17 | 152 days | 100% |
Planting calendar for Valier
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 16 – Jun 22 |
| Tomatoes | Transplant outdoors | Jun 2 – Jun 4 |
| Peppers | Start seeds indoors | Apr 16 – May 17 |
| Peppers | Transplant outdoors | Jun 16 – Jul 17 |
| Eggplant | Start seeds indoors | May 3 – Jun 1 |
| Eggplant | Transplant outdoors | Jun 16 – Jul 17 |
| Cucumbers | Sow outdoors | Jun 16 – Jun 14 |
| Summer squash | Sow outdoors | Jun 2 – Jul 17 |
| Winter squash & pumpkins | Sow outdoors | Jun 16 – Jul 17 |
| Snap beans | Sow outdoors | Jun 2 – Jul 7 |
| Sweet corn | Sow outdoors | Jun 2 – Jun 4 |
| Watermelon & cantaloupe | Sow outdoors | Jun 16 – Jul 17 |
| Okra | Sow outdoors | Jun 9 – Jul 2 |
| Peas | Sow outdoors (spring) | Apr 16 – Jun 1 |
| Potatoes | Plant outdoors (spring) | Apr 16 – Jun 16 |
| Onions | Start seeds indoors (spring) | Mar 5 – Apr 1 |
| Onions | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (spring) | Mar 29 – May 2 |
| Broccoli | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (fall) | May 25 – Jun 4 |
| Broccoli | Transplant outdoors (fall) | Jun 24 – Jul 5 |
| Cabbage | Start seeds indoors (spring) | Mar 19 – Apr 16 |
| Cabbage | Transplant outdoors (spring) | Apr 16 – May 17 |
| Cabbage | Start seeds indoors (fall) | May 15 – Jun 14 |
| Cabbage | Transplant outdoors (fall) | Jun 14 – Jul 15 |
| Leaf lettuce | Sow outdoors (spring) | Apr 16 – Jul 2 |
| Leaf lettuce | Sow outdoors (fall) | Jun 14 – Jul 31 |
| Spinach | Sow outdoors (spring) | Apr 9 – May 23 |
| Spinach | Sow outdoors (fall) | Jul 1 – Aug 5 |
| Radishes | Sow outdoors (spring) | Apr 16 – Jun 6 |
| Radishes | Sow outdoors (fall) | Jun 14 – Aug 15 |
| Kale | Sow outdoors (spring) | May 3 – May 23 |
| Kale | Sow outdoors (fall) | Jun 7 – Jul 15 |
| Carrots | Sow outdoors (spring) | May 17 – Jul 2 |
| Carrots | Sow outdoors (fall) | May 15 – Jun 30 |
| Garlic | Plant outdoors (fall) | Sep 14 – Oct 15 |
Where these dates come from
ZIP code 59486 is matched to the NOAA station Valier, MT, 5.4 km away, at 3,807 ft elevation (12 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Valier, MT (used) | 3,807 ft | May 17 | Sep 24 |
| Conrad, MT | 3,550 ft | May 20 | Sep 19 |
| Blackleaf, MT | 4,235 ft | Jun 9 | Sep 3 |
| Cut Bank Muni Ap, MT | 3,838 ft | May 24 | Sep 15 |
Frost dates near Valier
- Dupuyer, MT 59432 · last Jun 9, first Sep 3
- Pendroy, MT 59467 · last Jun 9, first Sep 3
- Conrad, MT 59425 · last May 20, first Sep 19
- Bynum, MT 59419 · last May 28, first Sep 12
- Ethridge, MT 59435 · last May 23, first Sep 16
- Heart Butte, MT 59448 · last Jun 8, first Sep 5
- Shelby, MT 59474 · last May 23, first Sep 16
- Cut Bank, MT 59427 · last May 24, first Sep 15
Frequently asked questions
- When is the last frost in Valier, MT?
- For ZIP code 59486, the average last spring frost (32°F) is May 17, based on NOAA 1991-2020 climate normals for the Valier, MT weather station. There is a 1-in-10 chance of a frost after May 31.
- When is the first frost in Valier, MT?
- The average first fall frost (32°F) is September 24. There is a 1-in-10 chance of frost by September 11, so tender plants are at risk from that point on.
- How long is the growing season in 59486?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 129 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.