Frost dates for 59848Lonepine, MT
The average last spring frost in Lonepine is May 15 and the average first fall frost is September 28, giving a typical growing season of about 134 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 15
- Average first fall frost
- Sep 28
- Growing season
- 134 days
Safer after Jun 1 (1-in-10 risk)
Possible by Sep 13 (1-in-10 risk)
Last frost typically in 200 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 · Jun 2 · Jun 21 | Sep 1 · Sep 15 · Sep 29 | 103 days | 100% |
| Frost / freeze (32°F) | May 3 · May 15 · Jun 1 | Sep 13 · Sep 28 · Oct 11 | 134 days | 100% |
| Hard freeze (28°F) | Apr 17 · May 2 · May 17 | Sep 24 · Oct 8 · Oct 24 | 158 days | 100% |
Planting calendar for Lonepine
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 14 – Jun 20 |
| Tomatoes | Transplant outdoors | May 31 – Jun 8 |
| Peppers | Start seeds indoors | Apr 14 – May 15 |
| Peppers | Transplant outdoors | Jun 14 – Jul 15 |
| Eggplant | Start seeds indoors | May 1 – May 30 |
| Eggplant | Transplant outdoors | Jun 14 – Jul 15 |
| Cucumbers | Sow outdoors | Jun 14 – Jun 18 |
| Summer squash | Sow outdoors | May 31 – Jul 15 |
| Winter squash & pumpkins | Sow outdoors | Jun 14 – Jul 15 |
| Snap beans | Sow outdoors | May 31 – Jul 11 |
| Sweet corn | Sow outdoors | May 31 – Jun 8 |
| Watermelon & cantaloupe | Sow outdoors | Jun 14 – Jul 15 |
| Okra | Sow outdoors | Jun 7 – Jun 30 |
| Peas | Sow outdoors (spring) | Apr 14 – May 30 |
| Potatoes | Plant outdoors (spring) | Apr 14 – Jun 14 |
| Onions | Start seeds indoors (spring) | Mar 3 – Mar 30 |
| Onions | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (spring) | Mar 27 – Apr 30 |
| Broccoli | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (fall) | May 29 – Jun 8 |
| Broccoli | Transplant outdoors (fall) | Jun 28 – Jul 9 |
| Cabbage | Start seeds indoors (spring) | Mar 17 – Apr 14 |
| Cabbage | Transplant outdoors (spring) | Apr 14 – May 15 |
| Cabbage | Start seeds indoors (fall) | May 19 – Jun 18 |
| Cabbage | Transplant outdoors (fall) | Jun 18 – Jul 19 |
| Leaf lettuce | Sow outdoors (spring) | Apr 14 – Jun 30 |
| Leaf lettuce | Sow outdoors (fall) | Jun 18 – Aug 4 |
| Spinach | Sow outdoors (spring) | Apr 7 – May 21 |
| Spinach | Sow outdoors (fall) | Jul 5 – Aug 9 |
| Radishes | Sow outdoors (spring) | Apr 14 – Jun 4 |
| Radishes | Sow outdoors (fall) | Jun 18 – Aug 19 |
| Kale | Sow outdoors (spring) | May 1 – May 21 |
| Kale | Sow outdoors (fall) | Jun 11 – Jul 19 |
| Carrots | Sow outdoors (spring) | May 15 – Jun 30 |
| Carrots | Sow outdoors (fall) | May 19 – Jul 4 |
| Garlic | Plant outdoors (fall) | Sep 18 – Oct 19 |
Where these dates come from
ZIP code 59848 is matched to the NOAA station Skq Dam, MT, 31.5 km away, at 2,730 ft elevation (46 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Skq Dam, MT (used) | 2,730 ft | May 15 | Sep 28 |
| Polson, MT | 3,010 ft | May 10 | Oct 5 |
| Libby 32 Sse, MT | 3,440 ft | — | — |
| Bigfork 13 S, MT | 2,979 ft | May 1 | Oct 15 |
Frost dates near Lonepine
- Hot Springs, MT 59845 · last May 10, first Oct 5
- Elmo, MT 59915 · last May 10, first Oct 5
- Big Arm, MT 59910 · last May 10, first Oct 5
- Proctor, MT 59929 · last May 1, first Oct 15
- Dayton, MT 59914 · last May 1, first Oct 15
- Plains, MT 59859 · last —, first —
- Rollins, MT 59931 · last May 1, first Oct 15
- Polson, MT 59860 · last May 10, first Oct 5
Frequently asked questions
- When is the last frost in Lonepine, MT?
- For ZIP code 59848, the average last spring frost (32°F) is May 15, based on NOAA 1991-2020 climate normals for the Skq Dam, MT weather station. There is a 1-in-10 chance of a frost after June 1.
- When is the first frost in Lonepine, MT?
- The average first fall frost (32°F) is September 28. There is a 1-in-10 chance of frost by September 13, so tender plants are at risk from that point on.
- How long is the growing season in 59848?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 134 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.