Clayton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.3 °F (low) to 56.7 °F (high). Annual precipitation averages 37.5 Inches. Clayton is located in USDA Plant Hardiness Zone 5a. 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 | 9.3 °F | 26.2 °F | 1.25 in. |
| February | 12.8 °F | 30.9 °F | 1.23 in. |
| March | 24.8 °F | 43.5 °F | 1.99 in. |
| April | 36.4 °F | 57.6 °F | 3.79 in. |
| May | 48.1 °F | 69.3 °F | 4.63 in. |
| June | 58.4 °F | 78.8 °F | 5.79 in. |
| July | 62.3 °F | 82.3 °F | 4.63 in. |
| August | 60.1 °F | 80.5 °F | 3.89 in. |
| September | 51.7 °F | 73.7 °F | 3.82 in. |
| October | 39.6 °F | 60.7 °F | 2.81 in. |
| November | 27.5 °F | 44.9 °F | 2.08 in. |
| December | 16.5 °F | 31.9 °F | 1.59 in. |
| Annual | 37.3 °F | 56.7 °F | 37.5 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |