Clayton, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 34.3 °F (low) to 57.9 °F (high). Annual precipitation averages 25.8 Inches. Clayton is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 21.6 °F | 34.1 °F | 3.35 in. |
| February | 22.5 °F | 39.4 °F | 2.1 in. |
| March | 27.3 °F | 48.4 °F | 2.74 in. |
| April | 32.3 °F | 56.9 °F | 1.84 in. |
| May | 39.8 °F | 66.8 °F | 2.19 in. |
| June | 45.4 °F | 73.2 °F | 2.07 in. |
| July | 49.9 °F | 83.9 °F | 0.71 in. |
| August | 48.8 °F | 84.4 °F | 0.62 in. |
| September | 41.7 °F | 74.0 °F | 0.82 in. |
| October | 33.1 °F | 58.1 °F | 2.15 in. |
| November | 27.2 °F | 42.5 °F | 3.13 in. |
| December | 21.8 °F | 33.5 °F | 4.03 in. |
| Annual | 34.3 °F | 57.9 °F | 25.75 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |