| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F |
| 1990 Hardiness Zone: | Zone 7a: 0F to 5F |
| Average First Frost Date: | Sep.1 - Sep. 10 |
| Average Last Frost Date: | Jul. 1 - Jul. 10 |
| Koppen-Geiger Climate Zone: | Dsb - Humid Continental Climate - Dry Cool Summer |
| Ecoregion: | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 96122 - Portola, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 19 | 22 | 26 | 29 | 35 | 40 | 43 | 42 | 37 | 30 | 24 | 19 | 31 |
| Avg Max Temp (°F) | 42 | 45 | 50 | 57 | 66 | 76 | 84 | 84 | 77 | 65 | 50 | 42 | 61 |
| Avg Precip (In.) | 4.1 | 3.89 | 3.58 | 1.26 | 1.11 | .54 | .34 | .43 | .78 | 1.27 | 2.6 | 3.27 | 23.16 |