Keswick, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.6 °C (low) to 24.2 °C (high). Annual precipitation averages 1317.7 Millimeters. Keswick is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 1 - Feb. 10 through the first frost around Dec. 11 - Dec. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.1 °C | 13.4 °C | 227.84 mm |
| February | 4.1 °C | 15.6 °C | 231.39 mm |
| March | 5.4 °C | 18.2 °C | 195.58 mm |
| April | 7.4 °C | 21.6 °C | 95.5 mm |
| May | 11.4 °C | 26.9 °C | 67.06 mm |
| June | 15.3 °C | 32 °C | 32.26 mm |
| July | 18.1 °C | 36.8 °C | 2.54 mm |
| August | 17.1 °C | 36.1 °C | 4.57 mm |
| September | 14.5 °C | 33.2 °C | 12.95 mm |
| October | 10.2 °C | 26.2 °C | 60.96 mm |
| November | 5.5 °C | 17.6 °C | 139.19 mm |
| December | 2.9 °C | 12.8 °C | 247.9 mm |
| Annual | 9.6 °C | 24.2 °C | 1317.74 mm |
| Average First Frost Date | Dec. 11 - Dec. 20 |
| Average Last Frost Date | Feb. 1 - Feb. 10 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |