Westwood, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from -0.1 °C (low) to 15.5 °C (high). Annual precipitation averages 1017.3 Millimeters. Westwood is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.7 °C | 5.6 °C | 183.39 mm |
| February | -6 °C | 6.9 °C | 162.81 mm |
| March | -4.1 °C | 9.8 °C | 153.92 mm |
| April | -1.6 °C | 12 °C | 82.8 mm |
| May | 2 °C | 17.4 °C | 51.56 mm |
| June | 5.1 °C | 22.8 °C | 23.11 mm |
| July | 8.3 °C | 28.1 °C | 8.13 mm |
| August | 7.2 °C | 27.7 °C | 7.11 mm |
| September | 4.1 °C | 24.3 °C | 9.91 mm |
| October | 0.1 °C | 17.2 °C | 51.56 mm |
| November | -3.6 °C | 9.8 °C | 99.31 mm |
| December | -6.5 °C | 4.9 °C | 183.64 mm |
| Annual | -0.1 °C | 15.5 °C | 1017.25 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |