Carroll, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.6 °F (low) to 58.6 °F (high). Annual precipitation averages 33.4 Inches. Carroll 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 10.3 °F | 27.9 °F | 0.84 in. |
| February | 14.3 °F | 32.6 °F | 1.1 in. |
| March | 25.3 °F | 46.0 °F | 1.96 in. |
| April | 36.1 °F | 59.9 °F | 3.44 in. |
| May | 48.9 °F | 70.9 °F | 4.66 in. |
| June | 59.7 °F | 81.2 °F | 5.07 in. |
| July | 63.2 °F | 84.0 °F | 4.13 in. |
| August | 60.4 °F | 81.8 °F | 4.03 in. |
| September | 51.2 °F | 76.2 °F | 2.96 in. |
| October | 39.1 °F | 63.1 °F | 2.54 in. |
| November | 26.4 °F | 46.4 °F | 1.42 in. |
| December | 16.1 °F | 33.1 °F | 1.25 in. |
| Annual | 37.6 °F | 58.6 °F | 33.4 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |