Frost dates for 59901Kalispell, MT
The average last spring frost in Kalispell is May 31 and the average first fall frost is September 10, giving a typical growing season of about 100 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 31
- Average first fall frost
- Sep 10
- Growing season
- 100 days
Safer after Jun 22 (1-in-10 risk)
Possible by Aug 26 (1-in-10 risk)
Last frost typically in 216 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) | — | — | 60 days | 100% |
| Frost / freeze (32°F) | May 13 · May 31 · Jun 22 | Aug 26 · Sep 10 · Sep 25 | 100 days | 100% |
| Hard freeze (28°F) | Apr 28 · May 10 · May 26 | Sep 9 · Sep 27 · Oct 7 | 136 days | 100% |
Planting calendar for Kalispell
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 30 – Jul 6 |
| Tomatoes | Transplant outdoors | Jun 16 – May 21 |
| Peppers | Start seeds indoors | Apr 30 – May 31 |
| Peppers | Transplant outdoors | Jun 30 – Jul 31 |
| Eggplant | Start seeds indoors | May 17 – Jun 15 |
| Eggplant | Transplant outdoors | Jun 30 – Jul 31 |
| Cucumbers | Sow outdoors | Jun 30 – May 31 |
| Summer squash | Sow outdoors | Jun 16 – Jul 31 |
| Winter squash & pumpkins | Sow outdoors | Jun 30 – Jul 31 |
| Snap beans | Sow outdoors | Jun 16 – Jun 23 |
| Sweet corn | Sow outdoors | Jun 16 – May 21 |
| Watermelon & cantaloupe | Sow outdoors | Jun 30 – Jul 31 |
| Okra | Sow outdoors | Jun 23 – Jul 16 |
| Peas | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Potatoes | Plant outdoors (spring) | Apr 30 – Jun 30 |
| Onions | Start seeds indoors (spring) | Mar 19 – Apr 15 |
| Onions | Transplant outdoors (spring) | May 17 – Jun 15 |
| Broccoli | Start seeds indoors (spring) | Apr 12 – May 16 |
| Broccoli | Transplant outdoors (spring) | May 17 – Jun 15 |
| Broccoli | Start seeds indoors (fall) | May 11 – May 21 |
| Broccoli | Transplant outdoors (fall) | Jun 10 – Jun 21 |
| Cabbage | Start seeds indoors (spring) | Apr 2 – Apr 30 |
| Cabbage | Transplant outdoors (spring) | Apr 30 – May 31 |
| Cabbage | Start seeds indoors (fall) | May 1 – May 31 |
| Cabbage | Transplant outdoors (fall) | May 31 – Jul 1 |
| Leaf lettuce | Sow outdoors (spring) | Apr 30 – Jul 16 |
| Leaf lettuce | Sow outdoors (fall) | May 31 – Jul 17 |
| Spinach | Sow outdoors (spring) | Apr 23 – Jun 6 |
| Spinach | Sow outdoors (fall) | Jun 17 – Jul 22 |
| Radishes | Sow outdoors (spring) | Apr 30 – Jun 20 |
| Radishes | Sow outdoors (fall) | May 31 – Aug 1 |
| Kale | Sow outdoors (spring) | May 17 – Jun 6 |
| Kale | Sow outdoors (fall) | May 24 – Jul 1 |
| Carrots | Sow outdoors (spring) | May 31 – Jul 16 |
| Carrots | Sow outdoors (fall) | May 1 – Jun 16 |
| Garlic | Plant outdoors (fall) | Aug 31 – Oct 1 |
Where these dates come from
ZIP code 59901 is matched to the NOAA station Kalispell Glacier Ap, MT, 11.7 km away, at 2,957 ft elevation (12 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Kalispell Glacier Ap, MT (used) | 2,957 ft | May 31 | Sep 10 |
| Creston, MT | 2,935 ft | May 12 | Sep 25 |
| Whitefish, MT | 3,100 ft | May 16 | Sep 25 |
| Hungry Horse Dam, MT | 3,160 ft | May 9 | Oct 1 |
Frost dates near Kalispell
- Kalispell, MT 59904 · last May 31, first Sep 10
- Somers, MT 59932 · last May 12, first Sep 25
- Columbia Falls, MT 59912 · last May 31, first Sep 10
- Kila, MT 59920 · last May 31, first Sep 10
- Lakeside, MT 59922 · last May 12, first Sep 25
- Whitefish, MT 59937 · last May 16, first Sep 25
- Bigfork, MT 59911 · last May 12, first Sep 25
- Hungry Horse, MT 59919 · last May 9, first Oct 1
Frequently asked questions
- When is the last frost in Kalispell, MT?
- For ZIP code 59901, the average last spring frost (32°F) is May 31, based on NOAA 1991-2020 climate normals for the Kalispell Glacier Ap, MT weather station. There is a 1-in-10 chance of a frost after June 22.
- When is the first frost in Kalispell, MT?
- The average first fall frost (32°F) is September 10. There is a 1-in-10 chance of frost by August 26, so tender plants are at risk from that point on.
- How long is the growing season in 59901?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 100 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.