Frost Dates for Bozeman, MT
In Bozeman, MT, the average last spring frost is around May 26 and the average first fall frost around Sep 22, for a growing season of about 116 days. For frost-tender plants, wait until Jun 14, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Bozeman Montana State Univ, MT weather station, 1 mile away, elevation 4,913 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 14 | Sep 5 |
| 20% | Jun 8 | Sep 11 |
| 30% | Jun 3 | Sep 16 |
| 40% | May 31 | Sep 19 |
| 50% | May 26 | Sep 22 |
| 60% | May 23 | Sep 25 |
| 70% | May 19 | Sep 28 |
| 80% | May 15 | Oct 1 |
| 90% | May 9 | Oct 5 |
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) | Jun 14 | Sep 8 |
| Frost / freeze (32°F) | May 26 | Sep 22 |
| Hard freeze (28°F) | May 8 | Oct 3 |
Planting calendar for Bozeman
Transplant Jun 2 – Jun 16
Transplant Jun 9 – Jun 23
Transplant Jun 9 – Jun 23
Transplant Jun 2 – Jun 16
Sow or transplant Jun 2 – Jun 16
Sow or transplant Jun 2 – Jun 16
Sow or transplant Jun 9 – Jun 23
Sow or transplant Apr 28 – May 12
Fall sowing Jul 28 – Aug 25
Fall sowing Jul 28 – Aug 18
Fall sowing Jul 14 – Jul 28
Sow or transplant Apr 28 – May 12
Fall sowing Jul 14 – Aug 11
Transplant May 12 – May 26
Fall sowing Jun 30 – Jul 14
Transplant May 5 – May 19
Fall sowing Jun 30 – Jul 14
Fall sowing Jun 30 – Jul 14
Fall sowing Aug 11 – Sep 1
Fall sowing Jul 14 – Jul 28
Plant Apr 28 – May 12
Based on the average last frost (May 26) and first frost (Sep 22). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.