Frost dates for 59341Mildred, MT
The average last spring frost in Mildred is May 20 and the average first fall frost is September 22, giving a typical growing season of about 124 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 20
- Average first fall frost
- Sep 22
- Growing season
- 124 days
Safer after Jun 2 (1-in-10 risk)
Possible by Sep 7 (1-in-10 risk)
Last frost typically in 205 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 16 · May 29 · Jun 16 | Aug 27 · Sep 12 · Sep 26 | 103 days | 100% |
| Frost / freeze (32°F) | May 6 · May 20 · Jun 2 | Sep 7 · Sep 22 · Oct 6 | 124 days | 100% |
| Hard freeze (28°F) | Apr 23 · May 7 · May 23 | Sep 16 · Oct 1 · Oct 16 | 145 days | 100% |
Planting calendar for Mildred
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 19 – Jun 25 |
| Tomatoes | Transplant outdoors | Jun 5 – Jun 2 |
| Peppers | Start seeds indoors | Apr 19 – May 20 |
| Peppers | Transplant outdoors | Jun 19 – Jul 20 |
| Eggplant | Start seeds indoors | May 6 – Jun 4 |
| Eggplant | Transplant outdoors | Jun 19 – Jul 20 |
| Cucumbers | Sow outdoors | Jun 19 – Jun 12 |
| Summer squash | Sow outdoors | Jun 5 – Jul 20 |
| Winter squash & pumpkins | Sow outdoors | Jun 19 – Jul 20 |
| Snap beans | Sow outdoors | Jun 5 – Jul 5 |
| Sweet corn | Sow outdoors | Jun 5 – Jun 2 |
| Watermelon & cantaloupe | Sow outdoors | Jun 19 – Jul 20 |
| Okra | Sow outdoors | Jun 12 – Jul 5 |
| Peas | Sow outdoors (spring) | Apr 19 – Jun 4 |
| Potatoes | Plant outdoors (spring) | Apr 19 – Jun 19 |
| Onions | Start seeds indoors (spring) | Mar 8 – Apr 4 |
| Onions | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (spring) | Apr 1 – May 5 |
| Broccoli | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (fall) | May 23 – Jun 2 |
| Broccoli | Transplant outdoors (fall) | Jun 22 – Jul 3 |
| Cabbage | Start seeds indoors (spring) | Mar 22 – Apr 19 |
| Cabbage | Transplant outdoors (spring) | Apr 19 – May 20 |
| Cabbage | Start seeds indoors (fall) | May 13 – Jun 12 |
| Cabbage | Transplant outdoors (fall) | Jun 12 – Jul 13 |
| Leaf lettuce | Sow outdoors (spring) | Apr 19 – Jul 5 |
| Leaf lettuce | Sow outdoors (fall) | Jun 12 – Jul 29 |
| Spinach | Sow outdoors (spring) | Apr 12 – May 26 |
| Spinach | Sow outdoors (fall) | Jun 29 – Aug 3 |
| Radishes | Sow outdoors (spring) | Apr 19 – Jun 9 |
| Radishes | Sow outdoors (fall) | Jun 12 – Aug 13 |
| Kale | Sow outdoors (spring) | May 6 – May 26 |
| Kale | Sow outdoors (fall) | Jun 5 – Jul 13 |
| Carrots | Sow outdoors (spring) | May 20 – Jul 5 |
| Carrots | Sow outdoors (fall) | May 13 – Jun 28 |
| Garlic | Plant outdoors (fall) | Sep 12 – Oct 13 |
Where these dates come from
ZIP code 59341 is matched to the NOAA station Mildred 5 N, MT, 9.5 km away, at 2,482 ft elevation (120 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Mildred 5 N, MT (used) | 2,482 ft | May 20 | Sep 22 |
| Terry, MT | 2,250 ft | May 12 | Sep 28 |
| Plevna, MT | 2,780 ft | May 21 | Sep 20 |
| Carlyle 13 Nw, MT | 3,145 ft | May 18 | Sep 29 |
Frost dates near Mildred
- Fallon, MT 59326 · last May 20, first Sep 22
- Ismay, MT 59336 · last May 22, first Sep 15
- Terry, MT 59349 · last May 12, first Sep 28
- Plevna, MT 59344 · last May 21, first Sep 20
- Glendive, MT 59330 · last May 3, first Oct 4
- Kinsey, MT 59338 · last May 8, first Sep 30
- Lindsay, MT 59339 · last May 26, first Sep 17
- Baker, MT 59313 · last May 16, first Sep 26
Frequently asked questions
- When is the last frost in Mildred, MT?
- For ZIP code 59341, the average last spring frost (32°F) is May 20, based on NOAA 1991-2020 climate normals for the Mildred 5 N, MT weather station. There is a 1-in-10 chance of a frost after June 2.
- When is the first frost in Mildred, MT?
- The average first fall frost (32°F) is September 22. There is a 1-in-10 chance of frost by September 7, so tender plants are at risk from that point on.
- How long is the growing season in 59341?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 124 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.