Frost dates for 59087Winnett, MT
The average last spring frost in Winnett is May 16 and the average first fall frost is September 28, giving a typical growing season of about 132 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 16
- Average first fall frost
- Sep 28
- Growing season
- 132 days
Safer after May 31 (1-in-10 risk)
Possible by Sep 15 (1-in-10 risk)
Last frost typically in 194 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 15 · May 29 · Jun 14 | Sep 4 · Sep 17 · Sep 30 | 110 days | 100% |
| Frost / freeze (32°F) | May 3 · May 16 · May 31 | Sep 15 · Sep 28 · Oct 10 | 132 days | 100% |
| Hard freeze (28°F) | Apr 21 · May 3 · May 17 | Sep 24 · Oct 5 · Oct 20 | 153 days | 100% |
Planting calendar for Winnett
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 15 – Jun 21 |
| Tomatoes | Transplant outdoors | Jun 1 – Jun 8 |
| Peppers | Start seeds indoors | Apr 15 – May 16 |
| Peppers | Transplant outdoors | Jun 15 – Jul 16 |
| Eggplant | Start seeds indoors | May 2 – May 31 |
| Eggplant | Transplant outdoors | Jun 15 – Jul 16 |
| Cucumbers | Sow outdoors | Jun 15 – Jun 18 |
| Summer squash | Sow outdoors | Jun 1 – Jul 16 |
| Winter squash & pumpkins | Sow outdoors | Jun 15 – Jul 16 |
| Snap beans | Sow outdoors | Jun 1 – Jul 11 |
| Sweet corn | Sow outdoors | Jun 1 – Jun 8 |
| Watermelon & cantaloupe | Sow outdoors | Jun 15 – Jul 16 |
| Okra | Sow outdoors | Jun 8 – Jul 1 |
| Peas | Sow outdoors (spring) | Apr 15 – May 31 |
| Potatoes | Plant outdoors (spring) | Apr 15 – Jun 15 |
| Onions | Start seeds indoors (spring) | Mar 4 – Mar 31 |
| Onions | Transplant outdoors (spring) | May 2 – May 31 |
| Broccoli | Start seeds indoors (spring) | Mar 28 – May 1 |
| Broccoli | Transplant outdoors (spring) | May 2 – May 31 |
| Broccoli | Start seeds indoors (fall) | May 29 – Jun 8 |
| Broccoli | Transplant outdoors (fall) | Jun 28 – Jul 9 |
| Cabbage | Start seeds indoors (spring) | Mar 18 – Apr 15 |
| Cabbage | Transplant outdoors (spring) | Apr 15 – May 16 |
| Cabbage | Start seeds indoors (fall) | May 19 – Jun 18 |
| Cabbage | Transplant outdoors (fall) | Jun 18 – Jul 19 |
| Leaf lettuce | Sow outdoors (spring) | Apr 15 – Jul 1 |
| Leaf lettuce | Sow outdoors (fall) | Jun 18 – Aug 4 |
| Spinach | Sow outdoors (spring) | Apr 8 – May 22 |
| Spinach | Sow outdoors (fall) | Jul 5 – Aug 9 |
| Radishes | Sow outdoors (spring) | Apr 15 – Jun 5 |
| Radishes | Sow outdoors (fall) | Jun 18 – Aug 19 |
| Kale | Sow outdoors (spring) | May 2 – May 22 |
| Kale | Sow outdoors (fall) | Jun 11 – Jul 19 |
| Carrots | Sow outdoors (spring) | May 16 – Jul 1 |
| Carrots | Sow outdoors (fall) | May 19 – Jul 4 |
| Garlic | Plant outdoors (fall) | Sep 18 – Oct 19 |
Where these dates come from
ZIP code 59087 is matched to the NOAA station Flatwillow 4 Ene, MT, 14.2 km away, at 3,292 ft elevation (306 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Flatwillow 4 Ene, MT (used) | 3,292 ft | May 16 | Sep 28 |
| Grass Range, MT | 3,490 ft | May 20 | Sep 24 |
| Mosby 4 Ene, MT | 2,910 ft | May 5 | Oct 4 |
| Valentine, MT | 2,905 ft | May 18 | Sep 21 |
Frost dates near Winnett
- Teigen, MT 59084 · last May 20, first Sep 24
- Grass Range, MT 59032 · last May 20, first Sep 24
- Mosby, MT 59058 · last May 5, first Oct 4
- Musselshell, MT 59059 · last May 10, first Sep 29
- Melstone, MT 59054 · last May 10, first Sep 29
- Roundup, MT 59073 · last May 20, first Sep 21
- Forest Grove, MT 59441 · last May 23, first Sep 21
- Roy, MT 59471 · last May 14, first Sep 24
Frequently asked questions
- When is the last frost in Winnett, MT?
- For ZIP code 59087, the average last spring frost (32°F) is May 16, based on NOAA 1991-2020 climate normals for the Flatwillow 4 Ene, MT weather station. There is a 1-in-10 chance of a frost after May 31.
- When is the first frost in Winnett, MT?
- The average first fall frost (32°F) is September 28. There is a 1-in-10 chance of frost by September 15, so tender plants are at risk from that point on.
- How long is the growing season in 59087?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 132 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.