Frost dates in Boulder, MT
The average last spring frost in Boulder is around June 11 and the first fall frost is around September 7. That gives Boulder an average growing season of about 88 days.
Last spring frost
| Early (10% chance after) | May 20 |
|---|---|
| Average (50%) | June 11 |
| Late (90%) | June 28 |
First fall frost
| Early (10%) | August 26 |
|---|---|
| Average (50%) | September 7 |
| Late (90% chance before) | September 19 |