Frost dates in Shelby, MT
The average last spring frost in Shelby is around May 22 and the first fall frost is around September 19. That gives Shelby an average growing season of about 120 days.
Last spring frost
| Early (10% chance after) | May 4 |
|---|---|
| Average (50%) | May 22 |
| Late (90%) | June 10 |
First fall frost
| Early (10%) | September 3 |
|---|---|
| Average (50%) | September 19 |
| Late (90% chance before) | October 2 |