Frost dates in Circle, MT
The average last spring frost in Circle is around May 15 and the first fall frost is around September 19. That gives Circle an average growing season of about 127 days.
Last spring frost
| Early (10% chance after) | May 2 |
|---|---|
| Average (50%) | May 15 |
| Late (90%) | June 1 |
First fall frost
| Early (10%) | September 7 |
|---|---|
| Average (50%) | September 19 |
| Late (90% chance before) | October 2 |