Petaluma, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 45 °F (low) to 69.3 °F (high). Annual precipitation averages 27.6 Inches. Petaluma is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 21 - Feb. 29 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 38.3 °F | 56.7 °F | 5.92 in. |
| February | 39.9 °F | 60.4 °F | 6.17 in. |
| March | 41.5 °F | 63.8 °F | 3.29 in. |
| April | 43.1 °F | 66.1 °F | 1.6 in. |
| May | 46.5 °F | 70.7 °F | 0.86 in. |
| June | 49.9 °F | 76.6 °F | 0.29 in. |
| July | 52.0 °F | 79.7 °F | 0.01 in. |
| August | 52.4 °F | 80.1 °F | 0.06 in. |
| September | 50.2 °F | 80.3 °F | 0.08 in. |
| October | 46.4 °F | 75.2 °F | 1.09 in. |
| November | 41.3 °F | 64.8 °F | 2.45 in. |
| December | 37.9 °F | 56.9 °F | 5.81 in. |
| Annual | 45 °F | 69.3 °F | 27.63 in. |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 21 - Feb. 29 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |