Ross, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 8.7 °C (low) to 20.5 °C (high). Annual precipitation averages 1054.1 Millimeters. Ross is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 5.4 °C | 13.5 °C | 218.19 mm |
| February | 6.3 °C | 15.7 °C | 213.87 mm |
| March | 6.9 °C | 17.4 °C | 142.24 mm |
| April | 7.8 °C | 19.1 °C | 61.72 mm |
| May | 9.3 °C | 21.8 °C | 30.23 mm |
| June | 10.9 °C | 24.8 °C | 6.35 mm |
| July | 11.8 °C | 26.5 °C | 0.25 mm |
| August | 12.2 °C | 26.5 °C | 1.27 mm |
| September | 11.6 °C | 26.1 °C | 2.54 mm |
| October | 9.8 °C | 23.1 °C | 47.24 mm |
| November | 7.4 °C | 17.8 °C | 104.65 mm |
| December | 5.2 °C | 13.7 °C | 225.55 mm |
| Annual | 8.7 °C | 20.5 °C | 1054.1 mm |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 10a : -1.1°C to 1.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |