Frost dates in Westby, MT
The average last spring frost in Westby is around May 15 and the first fall frost is around September 18. That gives Westby an average growing season of about 126 days.
Last spring frost
| Early (10% chance after) | May 6 |
|---|---|
| Average (50%) | May 15 |
| Late (90%) | June 3 |
First fall frost
| Early (10%) | September 7 |
|---|---|
| Average (50%) | September 18 |
| Late (90% chance before) | October 4 |