Downieville, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 4.4 °C (low) to 20.1 °C (high). Annual precipitation averages 1656.6 Millimeters. Downieville is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -0.8 °C | 9.6 °C | 323.34 mm |
| February | -0.3 °C | 11.8 °C | 284.99 mm |
| March | 0.8 °C | 14.6 °C | 243.33 mm |
| April | 2.3 °C | 17.2 °C | 132.33 mm |
| May | 5.8 °C | 22.1 °C | 95.5 mm |
| June | 8.6 °C | 27.3 °C | 23.62 mm |
| July | 11.9 °C | 31.8 °C | 2.03 mm |
| August | 11.3 °C | 31.8 °C | 4.83 mm |
| September | 8.7 °C | 28.9 °C | 17.27 mm |
| October | 4.6 °C | 22.7 °C | 79.76 mm |
| November | 0.9 °C | 14.1 °C | 154.18 mm |
| December | -0.9 °C | 8.7 °C | 295.4 mm |
| Annual | 4.4 °C | 20.1 °C | 1656.58 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |