Frost dates for 59903Kalispell, MT
The average last spring frost in Kalispell is May 16 and the average first fall frost is September 25, giving a typical growing season of about 129 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 16
- Average first fall frost
- Sep 25
- Growing season
- 129 days
Safer after Jun 6 (1-in-10 risk)
Possible by Sep 8 (1-in-10 risk)
Last frost typically in 201 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 21 · Jun 7 · Jun 29 | Aug 24 · Sep 10 · Sep 24 | 93 days | 100% |
| Frost / freeze (32°F) | May 2 · May 16 · Jun 6 | Sep 8 · Sep 25 · Oct 8 | 129 days | 100% |
| Hard freeze (28°F) | Apr 19 · May 1 · May 14 | Sep 24 · Oct 7 · Oct 21 | 157 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 15 – Jun 21 |
| Tomatoes | Transplant outdoors | Jun 1 – Jun 5 |
| Peppers | Start seeds indoors | Apr 15 – May 16 |
| Peppers | Transplant outdoors | Jun 15 – Jul 16 |
| Eggplant | Start seeds indoors | May 2 – May 31 |
| Eggplant | Transplant outdoors | Jun 15 – Jul 16 |
| Cucumbers | Sow outdoors | Jun 15 – Jun 15 |
| Summer squash | Sow outdoors | Jun 1 – Jul 16 |
| Winter squash & pumpkins | Sow outdoors | Jun 15 – Jul 16 |
| Snap beans | Sow outdoors | Jun 1 – Jul 8 |
| Sweet corn | Sow outdoors | Jun 1 – Jun 5 |
| Watermelon & cantaloupe | Sow outdoors | Jun 15 – Jul 16 |
| Okra | Sow outdoors | Jun 8 – Jul 1 |
| Peas | Sow outdoors (spring) | Apr 15 – May 31 |
| Potatoes | Plant outdoors (spring) | Apr 15 – Jun 15 |
| Onions | Start seeds indoors (spring) | Mar 4 – Mar 31 |
| Onions | Transplant outdoors (spring) | May 2 – May 31 |
| Broccoli | Start seeds indoors (spring) | Mar 28 – May 1 |
| Broccoli | Transplant outdoors (spring) | May 2 – May 31 |
| Broccoli | Start seeds indoors (fall) | May 26 – Jun 5 |
| Broccoli | Transplant outdoors (fall) | Jun 25 – Jul 6 |
| Cabbage | Start seeds indoors (spring) | Mar 18 – Apr 15 |
| Cabbage | Transplant outdoors (spring) | Apr 15 – May 16 |
| Cabbage | Start seeds indoors (fall) | May 16 – Jun 15 |
| Cabbage | Transplant outdoors (fall) | Jun 15 – Jul 16 |
| Leaf lettuce | Sow outdoors (spring) | Apr 15 – Jul 1 |
| Leaf lettuce | Sow outdoors (fall) | Jun 15 – Aug 1 |
| Spinach | Sow outdoors (spring) | Apr 8 – May 22 |
| Spinach | Sow outdoors (fall) | Jul 2 – Aug 6 |
| Radishes | Sow outdoors (spring) | Apr 15 – Jun 5 |
| Radishes | Sow outdoors (fall) | Jun 15 – Aug 16 |
| Kale | Sow outdoors (spring) | May 2 – May 22 |
| Kale | Sow outdoors (fall) | Jun 8 – Jul 16 |
| Carrots | Sow outdoors (spring) | May 16 – Jul 1 |
| Carrots | Sow outdoors (fall) | May 16 – Jul 1 |
| Garlic | Plant outdoors (fall) | Sep 15 – Oct 16 |
Where these dates come from
ZIP code 59903 is matched to the NOAA station Whitefish, MT, 21.2 km away, at 3,100 ft elevation (338 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Whitefish, MT (used) | 3,100 ft | May 16 | Sep 25 |
| Kalispell Glacier Ap, MT | 2,957 ft | May 31 | Sep 10 |
| Creston, MT | 2,935 ft | May 12 | Sep 25 |
| Hungry Horse Dam, MT | 3,160 ft | May 9 | Oct 1 |
Frost dates near Kalispell
- Kalispell, MT 59901 · last May 31, first Sep 10
- Kila, MT 59920 · last May 31, first Sep 10
- Whitefish, MT 59937 · last May 16, first Sep 25
- Somers, MT 59932 · last May 12, first Sep 25
- Columbia Falls, MT 59912 · last May 31, first Sep 10
- Lakeside, MT 59922 · last May 12, first Sep 25
- Marion, MT 59925 · last —, first —
- Proctor, MT 59929 · last May 1, first Oct 15
Frequently asked questions
- When is the last frost in Kalispell, MT?
- For ZIP code 59903, the average last spring frost (32°F) is May 16, based on NOAA 1991-2020 climate normals for the Whitefish, MT weather station. There is a 1-in-10 chance of a frost after June 6.
- When is the first frost in Kalispell, MT?
- The average first fall frost (32°F) is September 25. There is a 1-in-10 chance of frost by September 8, so tender plants are at risk from that point on.
- How long is the growing season in 59903?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 129 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.