Frost dates in Portola, CA
The average last spring frost in Portola is around June 29 and the first fall frost is around August 21. That gives Portola an average growing season of about 53 days.
Last spring frost
| Early (10% chance after) | June 1 |
|---|---|
| Average (50%) | June 29 |
| Late (90%) | July 31 |
First fall frost
| Early (10%) | August 2 |
|---|---|
| Average (50%) | August 21 |
| Late (90% chance before) | September 23 |