Kelley, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.5 °F (low) to 58.7 °F (high). Annual precipitation averages 37.2 Inches. Kelley is located in USDA Plant Hardiness Zone 5b. 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 | 10.9 °F | 28.3 °F | 0.93 in. |
| February | 15.0 °F | 32.8 °F | 1.15 in. |
| March | 26.4 °F | 45.9 °F | 2.06 in. |
| April | 37.7 °F | 60.3 °F | 3.8 in. |
| May | 49.9 °F | 70.9 °F | 5.19 in. |
| June | 60.3 °F | 80.5 °F | 5.44 in. |
| July | 63.8 °F | 83.8 °F | 4.41 in. |
| August | 61.2 °F | 81.6 °F | 4.54 in. |
| September | 52.5 °F | 76.1 °F | 3.64 in. |
| October | 40.0 °F | 62.8 °F | 2.74 in. |
| November | 27.8 °F | 47.3 °F | 1.87 in. |
| December | 17.0 °F | 33.7 °F | 1.42 in. |
| Annual | 38.5 °F | 58.7 °F | 37.19 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 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |