Costa Mesa, California has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 55.1 °F (low) to 71.8 °F (high). Annual precipitation averages 11.6 Inches. Costa Mesa is located in USDA Plant Hardiness Zone 10b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 47.0 °F | 67.1 °F | 2.6 in. |
| February | 47.9 °F | 66.9 °F | 2.98 in. |
| March | 50.4 °F | 68.1 °F | 1.65 in. |
| April | 52.4 °F | 68.6 °F | 0.65 in. |
| May | 56.7 °F | 70.2 °F | 0.25 in. |
| June | 60.1 °F | 72.6 °F | 0.09 in. |
| July | 63.4 °F | 76.7 °F | 0.07 in. |
| August | 64.1 °F | 78.8 °F | 0.01 in. |
| September | 62.6 °F | 78.7 °F | 0.11 in. |
| October | 58.0 °F | 75.4 °F | 0.44 in. |
| November | 51.4 °F | 72.1 °F | 0.74 in. |
| December | 46.7 °F | 66.9 °F | 1.96 in. |
| Annual | 55.1 °F | 71.8 °F | 11.55 in. |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10b : 35°F to 30°F |
| Plant Hardiness Zone - 2012 | Zone 10b : 35°F to 30°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |