Frost Dates for Kalispell, MT
In Kalispell, MT, the average last spring frost is around May 31 and the average first fall frost around Sep 10, for a growing season of about 100 days. For frost-tender plants, wait until Jun 22, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Kalispell Glacier Airport, MT weather station, 7 miles away, elevation 2,957 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | Jun 22 | Aug 26 |
| 20% | Jun 14 | Aug 31 |
| 30% | Jun 7 | Sep 4 |
| 40% | Jun 3 | Sep 7 |
| 50% | May 31 | Sep 10 |
| 60% | May 27 | Sep 13 |
| 70% | May 23 | Sep 17 |
| 80% | May 19 | Sep 21 |
| 90% | May 13 | Sep 25 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | — | — |
| Frost / freeze (32°F) | May 31 | Sep 10 |
| Hard freeze (28°F) | May 10 | Sep 27 |
Planting calendar for Kalispell
Transplant Jun 7 – Jun 21
Transplant Jun 14 – Jun 28
Transplant Jun 14 – Jun 28
Transplant Jun 7 – Jun 21
Sow or transplant Jun 7 – Jun 21
Sow or transplant Jun 7 – Jun 21
Sow or transplant Jun 14 – Jun 28
Sow or transplant May 3 – May 17
Fall sowing Jul 16 – Aug 13
Fall sowing Jul 16 – Aug 6
Fall sowing Jul 2 – Jul 16
Sow or transplant May 3 – May 17
Fall sowing Jul 2 – Jul 30
Transplant May 17 – May 31
Fall sowing Jun 18 – Jul 2
Transplant May 10 – May 24
Fall sowing Jun 18 – Jul 2
Fall sowing Jun 18 – Jul 2
Fall sowing Jul 30 – Aug 20
Fall sowing Jul 2 – Jul 16
Plant May 3 – May 17
Based on the average last frost (May 31) and first frost (Sep 10). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.