Milton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.2 °C (low) to 16.5 °C (high). Annual precipitation averages 979.9 Millimeters. Milton 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 | -9.3 °C | 0.3 °C | 35.81 mm |
| February | -7.4 °C | 2.9 °C | 44.7 mm |
| March | -1.3 °C | 10.1 °C | 57.91 mm |
| April | 4.7 °C | 17.3 °C | 95.5 mm |
| May | 11.1 °C | 22.7 °C | 138.68 mm |
| June | 16.4 °C | 27.9 °C | 127.76 mm |
| July | 18.6 °C | 30.1 °C | 109.22 mm |
| August | 17.3 °C | 29.3 °C | 98.55 mm |
| September | 12.5 °C | 25.5 °C | 95 mm |
| October | 6.1 °C | 18.4 °C | 75.95 mm |
| November | -0.4 °C | 10.1 °C | 57.91 mm |
| December | -6.1 °C | 3.1 °C | 42.93 mm |
| Annual | 5.2 °C | 16.5 °C | 979.92 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |