Duvall, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 43.9 °F (low) to 60.8 °F (high). Annual precipitation averages 47.9 Inches. Duvall is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 35.4 °F | 46.7 °F | 6.22 in. |
| February | 35.5 °F | 49.7 °F | 4.44 in. |
| March | 37.9 °F | 53.8 °F | 4.97 in. |
| April | 41.4 °F | 59.1 °F | 4.14 in. |
| May | 46.8 °F | 65.9 °F | 2.93 in. |
| June | 51.1 °F | 69.9 °F | 2.59 in. |
| July | 54.5 °F | 76.7 °F | 1.04 in. |
| August | 54.6 °F | 77.6 °F | 1.11 in. |
| September | 50.6 °F | 71.7 °F | 2.35 in. |
| October | 44.5 °F | 60.9 °F | 4.75 in. |
| November | 39.0 °F | 51.3 °F | 6.97 in. |
| December | 35.1 °F | 45.8 °F | 6.42 in. |
| Annual | 43.9 °F | 60.8 °F | 47.93 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |