Westminster, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 55.1 °F (low) to 73 °F (high). Annual precipitation averages 12 Inches. Westminster is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 46.6 °F | 67.2 °F | 2.9 in. |
| February | 47.9 °F | 66.9 °F | 3.17 in. |
| March | 50.5 °F | 68.0 °F | 1.7 in. |
| April | 52.6 °F | 70.3 °F | 0.56 in. |
| May | 57.0 °F | 71.6 °F | 0.3 in. |
| June | 60.5 °F | 74.4 °F | 0.09 in. |
| July | 63.8 °F | 79.1 °F | 0.05 in. |
| August | 64.5 °F | 81.3 °F | 0.0 in. |
| September | 62.8 °F | 80.8 °F | 0.08 in. |
| October | 58.0 °F | 77.0 °F | 0.45 in. |
| November | 51.1 °F | 72.1 °F | 0.7 in. |
| December | 46.0 °F | 66.9 °F | 2.03 in. |
| Annual | 55.1 °F | 73 °F | 12.03 in. |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10a : 30°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 10b : 35°F to 30°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |