Frost dates for 59540Rudyard, MT
The average last spring frost in Rudyard is May 21 and the average first fall frost is September 19, giving a typical growing season of about 119 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 21
- Average first fall frost
- Sep 19
- Growing season
- 119 days
Safer after Jun 6 (1-in-10 risk)
Possible by Sep 3 (1-in-10 risk)
Last frost typically in 206 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 24 · Jun 6 · Jun 22 | Aug 22 · Sep 8 · Sep 21 | 93 days | 100% |
| Frost / freeze (32°F) | May 8 · May 21 · Jun 6 | Sep 3 · Sep 19 · Oct 1 | 119 days | 100% |
| Hard freeze (28°F) | Apr 25 · May 7 · May 23 | Sep 15 · Sep 29 · Oct 11 | 143 days | 100% |
Planting calendar for Rudyard
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 20 – Jun 26 |
| Tomatoes | Transplant outdoors | Jun 6 – May 30 |
| Peppers | Start seeds indoors | Apr 20 – May 21 |
| Peppers | Transplant outdoors | Jun 20 – Jul 21 |
| Eggplant | Start seeds indoors | May 7 – Jun 5 |
| Eggplant | Transplant outdoors | Jun 20 – Jul 21 |
| Cucumbers | Sow outdoors | Jun 20 – Jun 9 |
| Summer squash | Sow outdoors | Jun 6 – Jul 21 |
| Winter squash & pumpkins | Sow outdoors | Jun 20 – Jul 21 |
| Snap beans | Sow outdoors | Jun 6 – Jul 2 |
| Sweet corn | Sow outdoors | Jun 6 – May 30 |
| Watermelon & cantaloupe | Sow outdoors | Jun 20 – Jul 21 |
| Okra | Sow outdoors | Jun 13 – Jul 6 |
| Peas | Sow outdoors (spring) | Apr 20 – Jun 5 |
| Potatoes | Plant outdoors (spring) | Apr 20 – Jun 20 |
| Onions | Start seeds indoors (spring) | Mar 9 – Apr 5 |
| Onions | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (spring) | Apr 2 – May 6 |
| Broccoli | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (fall) | May 20 – May 30 |
| Broccoli | Transplant outdoors (fall) | Jun 19 – Jun 30 |
| Cabbage | Start seeds indoors (spring) | Mar 23 – Apr 20 |
| Cabbage | Transplant outdoors (spring) | Apr 20 – May 21 |
| Cabbage | Start seeds indoors (fall) | May 10 – Jun 9 |
| Cabbage | Transplant outdoors (fall) | Jun 9 – Jul 10 |
| Leaf lettuce | Sow outdoors (spring) | Apr 20 – Jul 6 |
| Leaf lettuce | Sow outdoors (fall) | Jun 9 – Jul 26 |
| Spinach | Sow outdoors (spring) | Apr 13 – May 27 |
| Spinach | Sow outdoors (fall) | Jun 26 – Jul 31 |
| Radishes | Sow outdoors (spring) | Apr 20 – Jun 10 |
| Radishes | Sow outdoors (fall) | Jun 9 – Aug 10 |
| Kale | Sow outdoors (spring) | May 7 – May 27 |
| Kale | Sow outdoors (fall) | Jun 2 – Jul 10 |
| Carrots | Sow outdoors (spring) | May 21 – Jul 6 |
| Carrots | Sow outdoors (fall) | May 10 – Jun 25 |
| Garlic | Plant outdoors (fall) | Sep 9 – Oct 10 |
Where these dates come from
ZIP code 59540 is matched to the NOAA station Joplin, MT, 16.2 km away, at 3,323 ft elevation (213 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Joplin, MT (used) | 3,323 ft | May 21 | Sep 19 |
| Gildford, MT | 2,820 ft | May 24 | Sep 15 |
| Rudyard 21 N, MT | 3,000 ft | May 30 | Sep 11 |
| Chester, MT | 3,132 ft | May 24 | Sep 17 |
Frost dates near Rudyard
- Hingham, MT 59528 · last May 24, first Sep 15
- Inverness, MT 59530 · last May 21, first Sep 19
- Joplin, MT 59531 · last May 21, first Sep 19
- Gildford, MT 59525 · last May 24, first Sep 15
- Chester, MT 59522 · last May 24, first Sep 17
- Kremlin, MT 59532 · last May 24, first Sep 15
- Lothair, MT 59461 · last May 24, first Sep 17
- Whitlash, MT 59545 · last —, first —
Frequently asked questions
- When is the last frost in Rudyard, MT?
- For ZIP code 59540, the average last spring frost (32°F) is May 21, based on NOAA 1991-2020 climate normals for the Joplin, MT weather station. There is a 1-in-10 chance of a frost after June 6.
- When is the first frost in Rudyard, MT?
- The average first fall frost (32°F) is September 19. There is a 1-in-10 chance of frost by September 3, so tender plants are at risk from that point on.
- How long is the growing season in 59540?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 119 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.