Sekiu, Washington has a Temperate Oceanic Climate climate (Köppen classification: Cfb). Average annual temperatures range from 43.7 °F (low) to 56.2 °F (high). Annual precipitation averages 81.7 Inches. Sekiu is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 37.9 °F | 46.8 °F | 13.91 in. |
| February | 37.3 °F | 48.3 °F | 8.3 in. |
| March | 38.7 °F | 50.7 °F | 9.12 in. |
| April | 41.0 °F | 55.2 °F | 5.48 in. |
| May | 45.0 °F | 59.4 °F | 3.06 in. |
| June | 49.1 °F | 62.5 °F | 2.17 in. |
| July | 51.3 °F | 65.3 °F | 1.46 in. |
| August | 51.8 °F | 66.2 °F | 1.58 in. |
| September | 49.4 °F | 64.5 °F | 2.44 in. |
| October | 45.1 °F | 58.1 °F | 7.39 in. |
| November | 40.4 °F | 50.9 °F | 13.33 in. |
| December | 37.1 °F | 46.5 °F | 13.44 in. |
| Annual | 43.7 °F | 56.2 °F | 81.68 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfb - Temperate Oceanic Climate |