Frost dates for 59489Winifred, MT
The average last spring frost in Winifred is May 16 and the average first fall frost is September 23, giving a typical growing season of about 127 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 16
- Average first fall frost
- Sep 23
- Growing season
- 127 days
Safer after May 30 (1-in-10 risk)
Possible by Sep 9 (1-in-10 risk)
Last frost typically in 201 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 17 · May 30 · Jun 15 | Aug 29 · Sep 12 · Sep 25 | 102 days | 100% |
| Frost / freeze (32°F) | May 5 · May 16 · May 30 | Sep 9 · Sep 23 · Oct 2 | 127 days | 100% |
| Hard freeze (28°F) | Apr 22 · May 5 · May 18 | Sep 21 · Oct 1 · Oct 14 | 149 days | 100% |
Planting calendar for Winifred
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 3 |
| 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 13 |
| Summer squash | Sow outdoors | Jun 1 – Jul 16 |
| Winter squash & pumpkins | Sow outdoors | Jun 15 – Jul 16 |
| Snap beans | Sow outdoors | Jun 1 – Jul 6 |
| Sweet corn | Sow outdoors | Jun 1 – Jun 3 |
| 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 24 – Jun 3 |
| Broccoli | Transplant outdoors (fall) | Jun 23 – Jul 4 |
| Cabbage | Start seeds indoors (spring) | Mar 18 – Apr 15 |
| Cabbage | Transplant outdoors (spring) | Apr 15 – May 16 |
| Cabbage | Start seeds indoors (fall) | May 14 – Jun 13 |
| Cabbage | Transplant outdoors (fall) | Jun 13 – Jul 14 |
| Leaf lettuce | Sow outdoors (spring) | Apr 15 – Jul 1 |
| Leaf lettuce | Sow outdoors (fall) | Jun 13 – Jul 30 |
| Spinach | Sow outdoors (spring) | Apr 8 – May 22 |
| Spinach | Sow outdoors (fall) | Jun 30 – Aug 4 |
| Radishes | Sow outdoors (spring) | Apr 15 – Jun 5 |
| Radishes | Sow outdoors (fall) | Jun 13 – Aug 14 |
| Kale | Sow outdoors (spring) | May 2 – May 22 |
| Kale | Sow outdoors (fall) | Jun 6 – Jul 14 |
| Carrots | Sow outdoors (spring) | May 16 – Jul 1 |
| Carrots | Sow outdoors (fall) | May 14 – Jun 29 |
| Garlic | Plant outdoors (fall) | Sep 13 – Oct 14 |
Where these dates come from
ZIP code 59489 is matched to the NOAA station Winifred, MT, 13.9 km away, at 3,243 ft elevation (5 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Winifred, MT (used) | 3,243 ft | May 16 | Sep 23 |
| Roy 8 Ne, MT | 3,085 ft | May 14 | Sep 24 |
| Sand Creek, MT | 2,910 ft | May 12 | Sep 27 |
| Zortman, MT | 4,035 ft | May 18 | Sep 23 |
Frost dates near Winifred
- Lloyd, MT 59535 · last May 23, first Sep 23
- Roy, MT 59471 · last May 14, first Sep 24
- Hilger, MT 59451 · last May 23, first Sep 21
- Zortman, MT 59546 · last May 12, first Sep 27
- Hays, MT 59527 · last May 18, first Sep 23
- Denton, MT 59430 · last Jun 1, first Sep 11
- Lewistown, MT 59457 · last May 23, first Sep 21
- Coffee Creek, MT 59424 · last Jun 1, first Sep 11
Frequently asked questions
- When is the last frost in Winifred, MT?
- For ZIP code 59489, the average last spring frost (32°F) is May 16, based on NOAA 1991-2020 climate normals for the Winifred, MT weather station. There is a 1-in-10 chance of a frost after May 30.
- When is the first frost in Winifred, MT?
- The average first fall frost (32°F) is September 23. There is a 1-in-10 chance of frost by September 9, so tender plants are at risk from that point on.
- How long is the growing season in 59489?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 127 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.