Willapa, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6 °C (low) to 15.4 °C (high). Annual precipitation averages 2099.3 Millimeters. Willapa is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.4 °C | 9 °C | 326.14 mm |
| February | 1.9 °C | 10.4 °C | 209.8 mm |
| March | 2.9 °C | 12.1 °C | 241.05 mm |
| April | 4.3 °C | 14.4 °C | 169.67 mm |
| May | 7.1 °C | 17.5 °C | 88.39 mm |
| June | 9.4 °C | 19.4 °C | 69.34 mm |
| July | 11.3 °C | 22 °C | 25.4 mm |
| August | 11.3 °C | 22.7 °C | 36.58 mm |
| September | 9.3 °C | 21.3 °C | 77.98 mm |
| October | 6.2 °C | 16.3 °C | 206.5 mm |
| November | 3.5 °C | 11.6 °C | 324.1 mm |
| December | 2 °C | 8.6 °C | 324.36 mm |
| Annual | 6 °C | 15.4 °C | 2099.31 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 | Csb - Warm-Summer Mediterranean Climate |