Maple Valley, Washington has a Temperate Oceanic Climate climate (Köppen classification: Cfb). Average annual temperatures range from 6.2 °C (low) to 15.7 °C (high). Annual precipitation averages 1259.3 Millimeters. Maple Valley 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 | 1.7 °C | 7.9 °C | 161.04 mm |
| February | 1.6 °C | 9.4 °C | 119.63 mm |
| March | 2.8 °C | 11.7 °C | 135.89 mm |
| April | 4.7 °C | 14.6 °C | 113.28 mm |
| May | 7.8 °C | 18.7 °C | 73.41 mm |
| June | 10.2 °C | 21 °C | 64.52 mm |
| July | 12.2 °C | 24.7 °C | 26.92 mm |
| August | 12.3 °C | 25 °C | 35.05 mm |
| September | 10 °C | 21.6 °C | 58.93 mm |
| October | 6.5 °C | 15.4 °C | 128.27 mm |
| November | 3.5 °C | 10.5 °C | 179.83 mm |
| December | 1.3 °C | 7.3 °C | 162.56 mm |
| Annual | 6.2 °C | 15.7 °C | 1259.33 mm |
| 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 : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfb - Temperate Oceanic Climate |