Rumsey, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.1 °C (low) to 24.3 °C (high). Annual precipitation averages 544.6 Millimeters. Rumsey is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.4 °C | 14.3 °C | 114.3 mm |
| February | 4.3 °C | 16.4 °C | 110.24 mm |
| March | 5.8 °C | 19 °C | 69.34 mm |
| April | 7.4 °C | 21.9 °C | 32 mm |
| May | 10.7 °C | 26.4 °C | 22.86 mm |
| June | 13.8 °C | 31.3 °C | 4.57 mm |
| July | 15.8 °C | 34.7 °C | 0.25 mm |
| August | 15.2 °C | 35 °C | 1.02 mm |
| September | 13.6 °C | 32.6 °C | 3.05 mm |
| October | 9.9 °C | 26.8 °C | 22.1 mm |
| November | 5.8 °C | 18.9 °C | 51.56 mm |
| December | 3.4 °C | 14.2 °C | 113.28 mm |
| Annual | 9.1 °C | 24.3 °C | 544.57 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |