Willow Creek, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.8 °C (low) to 22.6 °C (high). Annual precipitation averages 1285 Millimeters. Willow Creek is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.7 °C | 11 °C | 231.65 mm |
| February | 3.2 °C | 13.8 °C | 173.99 mm |
| March | 4.1 °C | 16.8 °C | 175.51 mm |
| April | 5.3 °C | 20.8 °C | 102.11 mm |
| May | 7.7 °C | 25.9 °C | 48.26 mm |
| June | 10 °C | 30.6 °C | 17.78 mm |
| July | 12.5 °C | 35.2 °C | 2.79 mm |
| August | 11.9 °C | 35.5 °C | 2.79 mm |
| September | 9.7 °C | 32.5 °C | 16 mm |
| October | 6.8 °C | 24.2 °C | 81.79 mm |
| November | 4.8 °C | 14.8 °C | 162.05 mm |
| December | 2.7 °C | 10.2 °C | 270.26 mm |
| Annual | 6.8 °C | 22.6 °C | 1284.98 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |