Frost dates in St. Helena, CA
The average last spring frost in St. Helena is around March 22 and the first fall frost is around November 14. That gives St. Helena an average growing season of about 237 days.
Last spring frost
| Early (10% chance after) | February 5 |
|---|---|
| Average (50%) | March 22 |
| Late (90%) | April 28 |
First fall frost
| Early (10%) | October 17 |
|---|---|
| Average (50%) | November 14 |
| Late (90% chance before) | December 4 |