Healdsburg, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.9 °C (low) to 22.3 °C (high). Annual precipitation averages 1080.3 Millimeters. Healdsburg is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 11 - Feb. 20 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.3 °C | 14.3 °C | 215.39 mm |
| February | 4.1 °C | 16.2 °C | 213.61 mm |
| March | 5.2 °C | 18.1 °C | 153.16 mm |
| April | 6.1 °C | 20.9 °C | 71.63 mm |
| May | 8 °C | 24.4 °C | 44.45 mm |
| June | 9.9 °C | 28 °C | 6.1 mm |
| July | 10.8 °C | 29.3 °C | 0.51 mm |
| August | 10.7 °C | 29.6 °C | 1.27 mm |
| September | 9.6 °C | 28.9 °C | 2.29 mm |
| October | 7.5 °C | 24.9 °C | 46.23 mm |
| November | 4.7 °C | 18.7 °C | 105.16 mm |
| December | 2.9 °C | 14.3 °C | 220.47 mm |
| Annual | 6.9 °C | 22.3 °C | 1080.27 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |