Ashton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 1.9 °C (low) to 13.4 °C (high). Annual precipitation averages 773.2 Millimeters. 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 | -13.9 °C | -4.1 °C | 19.3 mm |
| February | -11.6 °C | -1.6 °C | 22.1 mm |
| March | -5.2 °C | 5.6 °C | 42.16 mm |
| April | 1.3 °C | 14.1 °C | 81.03 mm |
| May | 8.4 °C | 21 °C | 104.9 mm |
| June | 14.6 °C | 26.6 °C | 120.9 mm |
| July | 16.4 °C | 28.2 °C | 88.65 mm |
| August | 15.1 °C | 26.9 °C | 87.88 mm |
| September | 10.1 °C | 23.5 °C | 82.8 mm |
| October | 2.9 °C | 16 °C | 60.45 mm |
| November | -4.4 °C | 6.4 °C | 36.83 mm |
| December | -10.6 °C | -1.3 °C | 26.16 mm |
| Annual | 1.9 °C | 13.4 °C | 773.16 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |