Ashton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 35.5 °F (low) to 56.2 °F (high). Annual precipitation averages 30.4 Inches. Ashton 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 | 7.0 °F | 24.6 °F | 0.76 in. |
| February | 11.2 °F | 29.2 °F | 0.87 in. |
| March | 22.7 °F | 42.0 °F | 1.66 in. |
| April | 34.3 °F | 57.3 °F | 3.19 in. |
| May | 47.2 °F | 69.8 °F | 4.13 in. |
| June | 58.3 °F | 79.8 °F | 4.76 in. |
| July | 61.6 °F | 82.8 °F | 3.49 in. |
| August | 59.1 °F | 80.5 °F | 3.46 in. |
| September | 50.1 °F | 74.3 °F | 3.26 in. |
| October | 37.2 °F | 60.8 °F | 2.38 in. |
| November | 24.1 °F | 43.5 °F | 1.45 in. |
| December | 12.9 °F | 29.6 °F | 1.03 in. |
| Annual | 35.5 °F | 56.2 °F | 30.44 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |