Clinton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.2 °F (low) to 59.5 °F (high). Annual precipitation averages 37.4 Inches. Clinton is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 13.6 °F | 29.9 °F | 1.54 in. |
| February | 17.2 °F | 34.4 °F | 1.77 in. |
| March | 28.0 °F | 47.1 °F | 2.49 in. |
| April | 39.1 °F | 60.6 °F | 3.6 in. |
| May | 50.9 °F | 71.9 °F | 4.47 in. |
| June | 60.9 °F | 81.1 °F | 5.0 in. |
| July | 64.4 °F | 84.2 °F | 4.0 in. |
| August | 62.2 °F | 82.3 °F | 3.9 in. |
| September | 53.9 °F | 76.2 °F | 3.65 in. |
| October | 42.2 °F | 63.4 °F | 2.73 in. |
| November | 30.4 °F | 48.1 °F | 2.32 in. |
| December | 20.0 °F | 35.3 °F | 1.91 in. |
| Annual | 40.2 °F | 59.5 °F | 37.38 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |