| 2023 Hardiness Zone: | Zone 9b: 25°F to 30°F Zone 10a: 30°F to 35°F |
| 2012 Hardiness Zone: | Zone 9b: 25°F to 30°F |
| 1990 Hardiness Zone: | Zone 9b: 25F to 30F |
| Average First Frost Date: | Dec. 11 - Dec. 20 |
| Average Last Frost Date: | Feb. 1 - Feb. 10 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 94027 - Atherton, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 39 | 41 | 43 | 45 | 48 | 52 | 54 | 54 | 53 | 48 | 42 | 38 | 46 |
| Avg Max Temp (°F) | 58 | 62 | 65 | 70 | 74 | 79 | 82 | 82 | 80 | 75 | 64 | 59 | 71 |
| Avg Precip (In.) | 4.16 | 4.01 | 3.37 | 1.1 | .43 | .11 | .04 | .09 | .22 | 1.04 | 2.55 | 2.9 | 20.02 |