Runnells, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.6 °F (low) to 60.6 °F (high). Annual precipitation averages 36.1 Inches. Runnells 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 | 13.5 °F | 31.0 °F | 0.99 in. |
| February | 17.1 °F | 35.5 °F | 1.28 in. |
| March | 28.2 °F | 48.6 °F | 2.06 in. |
| April | 39.7 °F | 62.2 °F | 3.79 in. |
| May | 51.8 °F | 71.9 °F | 5.1 in. |
| June | 62.1 °F | 81.7 °F | 5.23 in. |
| July | 65.7 °F | 85.4 °F | 4.28 in. |
| August | 63.2 °F | 83.9 °F | 4.19 in. |
| September | 54.5 °F | 77.5 °F | 3.52 in. |
| October | 42.1 °F | 64.0 °F | 2.6 in. |
| November | 30.0 °F | 49.1 °F | 1.75 in. |
| December | 19.3 °F | 36.1 °F | 1.29 in. |
| Annual | 40.6 °F | 60.6 °F | 36.08 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 |