Ross, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 47.7 °F (low) to 68.9 °F (high). Annual precipitation averages 41.5 Inches. Ross is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 41.8 °F | 56.3 °F | 8.59 in. |
| February | 43.3 °F | 60.3 °F | 8.42 in. |
| March | 44.4 °F | 63.4 °F | 5.6 in. |
| April | 46.1 °F | 66.3 °F | 2.43 in. |
| May | 48.8 °F | 71.3 °F | 1.19 in. |
| June | 51.7 °F | 76.7 °F | 0.25 in. |
| July | 53.3 °F | 79.7 °F | 0.01 in. |
| August | 53.9 °F | 79.7 °F | 0.05 in. |
| September | 52.9 °F | 78.9 °F | 0.1 in. |
| October | 49.6 °F | 73.5 °F | 1.86 in. |
| November | 45.4 °F | 64.0 °F | 4.12 in. |
| December | 41.3 °F | 56.6 °F | 8.88 in. |
| Annual | 47.7 °F | 68.9 °F | 41.5 in. |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 10a : 30°F to 25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |