Frost dates for 59013Boyd, MT
The average last spring frost in Boyd is May 29 and the average first fall frost is September 15, giving a typical growing season of about 107 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 29
- Average first fall frost
- Sep 15
- Growing season
- 107 days
Safer after Jun 17 (1-in-10 risk)
Possible by Sep 1 (1-in-10 risk)
Last frost typically in 207 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 30 · Jun 13 · Jun 30 | Aug 22 · Sep 4 · Sep 17 | 81 days | 100% |
| Frost / freeze (32°F) | May 14 · May 29 · Jun 17 | Sep 1 · Sep 15 · Oct 1 | 107 days | 100% |
| Hard freeze (28°F) | May 1 · May 13 · May 31 | Sep 11 · Sep 26 · Oct 9 | 134 days | 100% |
Planting calendar for Boyd
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 28 – Jul 4 |
| Tomatoes | Transplant outdoors | Jun 14 – May 26 |
| Peppers | Start seeds indoors | Apr 28 – May 29 |
| Peppers | Transplant outdoors | Jun 28 – Jul 29 |
| Eggplant | Start seeds indoors | May 15 – Jun 13 |
| Eggplant | Transplant outdoors | Jun 28 – Jul 29 |
| Cucumbers | Sow outdoors | Jun 28 – Jun 5 |
| Summer squash | Sow outdoors | Jun 14 – Jul 29 |
| Winter squash & pumpkins | Sow outdoors | Jun 28 – Jul 29 |
| Snap beans | Sow outdoors | Jun 14 – Jun 28 |
| Sweet corn | Sow outdoors | Jun 14 – May 26 |
| Watermelon & cantaloupe | Sow outdoors | Jun 28 – Jul 29 |
| Okra | Sow outdoors | Jun 21 – Jul 14 |
| Peas | Sow outdoors (spring) | Apr 28 – Jun 13 |
| Potatoes | Plant outdoors (spring) | Apr 28 – Jun 28 |
| Onions | Start seeds indoors (spring) | Mar 17 – Apr 13 |
| Onions | Transplant outdoors (spring) | May 15 – Jun 13 |
| Broccoli | Start seeds indoors (spring) | Apr 10 – May 14 |
| Broccoli | Transplant outdoors (spring) | May 15 – Jun 13 |
| Broccoli | Start seeds indoors (fall) | May 16 – May 26 |
| Broccoli | Transplant outdoors (fall) | Jun 15 – Jun 26 |
| Cabbage | Start seeds indoors (spring) | Mar 31 – Apr 28 |
| Cabbage | Transplant outdoors (spring) | Apr 28 – May 29 |
| Cabbage | Start seeds indoors (fall) | May 6 – Jun 5 |
| Cabbage | Transplant outdoors (fall) | Jun 5 – Jul 6 |
| Leaf lettuce | Sow outdoors (spring) | Apr 28 – Jul 14 |
| Leaf lettuce | Sow outdoors (fall) | Jun 5 – Jul 22 |
| Spinach | Sow outdoors (spring) | Apr 21 – Jun 4 |
| Spinach | Sow outdoors (fall) | Jun 22 – Jul 27 |
| Radishes | Sow outdoors (spring) | Apr 28 – Jun 18 |
| Radishes | Sow outdoors (fall) | Jun 5 – Aug 6 |
| Kale | Sow outdoors (spring) | May 15 – Jun 4 |
| Kale | Sow outdoors (fall) | May 29 – Jul 6 |
| Carrots | Sow outdoors (spring) | May 29 – Jul 14 |
| Carrots | Sow outdoors (fall) | May 6 – Jun 21 |
| Garlic | Plant outdoors (fall) | Sep 5 – Oct 6 |
Where these dates come from
ZIP code 59013 is matched to the NOAA station Joliet, MT, 4.7 km away, at 3,838 ft elevation (198 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Joliet, MT (used) | 3,838 ft | May 29 | Sep 15 |
| Bridger 2 N, MT | 3,583 ft | May 14 | Sep 24 |
| Columbus, MT | 3,602 ft | May 27 | Sep 14 |
| Red Lodge, MT | 5,646 ft | Jun 3 | Sep 19 |
Frost dates near Boyd
- Joliet, MT 59041 · last May 29, first Sep 15
- Roberts, MT 59070 · last May 29, first Sep 15
- Fromberg, MT 59029 · last May 14, first Sep 24
- Edgar, MT 59026 · last May 14, first Sep 24
- Park City, MT 59063 · last May 27, first Sep 14
- Bridger, MT 59014 · last May 14, first Sep 24
- Columbus, MT 59019 · last May 27, first Sep 14
- Absarokee, MT 59001 · last Jun 1, first Sep 11
Frequently asked questions
- When is the last frost in Boyd, MT?
- For ZIP code 59013, the average last spring frost (32°F) is May 29, based on NOAA 1991-2020 climate normals for the Joliet, MT weather station. There is a 1-in-10 chance of a frost after June 17.
- When is the first frost in Boyd, MT?
- The average first fall frost (32°F) is September 15. There is a 1-in-10 chance of frost by September 1, so tender plants are at risk from that point on.
- How long is the growing season in 59013?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 107 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.