Afton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.6 °F (low) to 60.2 °F (high). Annual precipitation averages 36.5 Inches. Afton 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 | 12.9 °F | 31.2 °F | 0.91 in. |
| February | 17.0 °F | 36.3 °F | 1.29 in. |
| March | 27.5 °F | 49.0 °F | 2.1 in. |
| April | 38.5 °F | 61.4 °F | 3.68 in. |
| May | 50.3 °F | 71.3 °F | 5.34 in. |
| June | 60.5 °F | 80.6 °F | 5.0 in. |
| July | 64.5 °F | 84.8 °F | 4.21 in. |
| August | 62.2 °F | 83.4 °F | 4.11 in. |
| September | 53.1 °F | 76.1 °F | 3.75 in. |
| October | 40.8 °F | 63.8 °F | 2.71 in. |
| November | 28.9 °F | 48.8 °F | 2.02 in. |
| December | 18.4 °F | 36.1 °F | 1.38 in. |
| Annual | 39.6 °F | 60.2 °F | 36.5 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 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |