Clayton, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 1.3 °C (low) to 14.4 °C (high). Annual precipitation averages 654.1 Millimeters. 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 | -5.8 °C | 1.2 °C | 85.09 mm |
| February | -5.3 °C | 4.1 °C | 53.34 mm |
| March | -2.6 °C | 9.1 °C | 69.6 mm |
| April | 0.2 °C | 13.8 °C | 46.74 mm |
| May | 4.3 °C | 19.3 °C | 55.63 mm |
| June | 7.4 °C | 22.9 °C | 52.58 mm |
| July | 9.9 °C | 28.8 °C | 18.03 mm |
| August | 9.3 °C | 29.1 °C | 15.75 mm |
| September | 5.4 °C | 23.3 °C | 20.83 mm |
| October | 0.6 °C | 14.5 °C | 54.61 mm |
| November | -2.7 °C | 5.8 °C | 79.5 mm |
| December | -5.7 °C | 0.8 °C | 102.36 mm |
| Annual | 1.3 °C | 14.4 °C | 654.06 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |