Frost dates in Hillsborough, CA
The average last spring frost in Hillsborough is around January 20 and the first fall frost is around December 16. That gives Hillsborough an average growing season of about 331 days.
Last spring frost
| Early (10% chance after) | January 3 |
|---|---|
| Average (50%) | January 20 |
| Late (90%) | February 13 |
First fall frost
| Early (10%) | December 3 |
|---|---|
| Average (50%) | December 16 |
| Late (90% chance before) | December 25 |