Sudden Valley, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 5.9 °C (low) to 14.2 °C (high). Annual precipitation averages 1185.2 Millimeters. Sudden Valley is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.1 °C | 6.4 °C | 159 mm |
| February | 0.9 °C | 8.1 °C | 84.07 mm |
| March | 2.3 °C | 10.8 °C | 131.83 mm |
| April | 4.5 °C | 13.2 °C | 96.77 mm |
| May | 7.6 °C | 17.2 °C | 71.37 mm |
| June | 10.4 °C | 19.3 °C | 54.1 mm |
| July | 12.7 °C | 22.8 °C | 28.45 mm |
| August | 12.7 °C | 23.4 °C | 28.45 mm |
| September | 9.8 °C | 20.2 °C | 63.5 mm |
| October | 6.5 °C | 14.3 °C | 134.87 mm |
| November | 2.7 °C | 9.1 °C | 175.26 mm |
| December | 0.4 °C | 5.9 °C | 157.48 mm |
| Annual | 5.9 °C | 14.2 °C | 1185.15 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |