Allerton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.3 °C (low) to 15.7 °C (high). Annual precipitation averages 993.2 Millimeters. Allerton is located in USDA Plant Hardiness Zone 5b. 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 | -10.4 °C | -0.3 °C | 28.19 mm |
| February | -8.3 °C | 2.4 °C | 36.58 mm |
| March | -2.3 °C | 9.6 °C | 58.17 mm |
| April | 3.7 °C | 16.1 °C | 99.31 mm |
| May | 10.2 °C | 21.6 °C | 138.18 mm |
| June | 15.7 °C | 26.8 °C | 144.53 mm |
| July | 18.2 °C | 29.3 °C | 116.59 mm |
| August | 16.7 °C | 28.4 °C | 108.97 mm |
| September | 11.7 °C | 24.7 °C | 97.28 mm |
| October | 5 °C | 17.7 °C | 75.69 mm |
| November | -1.9 °C | 9.4 °C | 50.55 mm |
| December | -7.3 °C | 2.8 °C | 39.12 mm |
| Annual | 4.3 °C | 15.7 °C | 993.16 mm |
| 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 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 |