Clayton, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 48 °F (low) to 66.6 °F (high). Annual precipitation averages 44 Inches. Clayton is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 24.3 °F | 40.4 °F | 2.7 in. |
| February | 27.4 °F | 45.9 °F | 2.34 in. |
| March | 36.4 °F | 56.1 °F | 3.51 in. |
| April | 47.2 °F | 67.8 °F | 4.69 in. |
| May | 57.9 °F | 76.8 °F | 5.19 in. |
| June | 67.0 °F | 85.4 °F | 4.6 in. |
| July | 70.6 °F | 88.9 °F | 4.1 in. |
| August | 68.8 °F | 87.6 °F | 3.79 in. |
| September | 60.5 °F | 81.0 °F | 3.35 in. |
| October | 49.3 °F | 69.4 °F | 3.41 in. |
| November | 37.6 °F | 55.3 °F | 3.6 in. |
| December | 29.1 °F | 44.8 °F | 2.76 in. |
| Annual | 48 °F | 66.6 °F | 44.04 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |