Frost dates in Chinook, MT
The average last spring frost in Chinook is around May 17 and the first fall frost is around September 16. That gives Chinook an average growing season of about 122 days.
Last spring frost
| Early (10% chance after) | May 2 |
|---|---|
| Average (50%) | May 17 |
| Late (90%) | June 3 |
First fall frost
| Early (10%) | September 3 |
|---|---|
| Average (50%) | September 16 |
| Late (90% chance before) | October 3 |