Fountain Valley, California has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 55.2 °F (low) to 72.8 °F (high). Annual precipitation averages 12 Inches. Fountain Valley is located in USDA Plant Hardiness Zone 10b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 46.9 °F | 67.2 °F | 2.86 in. |
| February | 48.0 °F | 67.0 °F | 3.14 in. |
| March | 50.6 °F | 68.1 °F | 1.69 in. |
| April | 52.7 °F | 70.1 °F | 0.59 in. |
| May | 57.0 °F | 71.5 °F | 0.26 in. |
| June | 60.5 °F | 74.2 °F | 0.08 in. |
| July | 63.8 °F | 78.5 °F | 0.06 in. |
| August | 64.4 °F | 80.7 °F | 0.0 in. |
| September | 62.9 °F | 80.4 °F | 0.1 in. |
| October | 58.2 °F | 76.8 °F | 0.45 in. |
| November | 51.2 °F | 72.1 °F | 0.72 in. |
| December | 46.4 °F | 66.9 °F | 2.08 in. |
| Annual | 55.2 °F | 72.8 °F | 12.03 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 |