Benton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.5 °C (low) to 16.2 °C (high). Annual precipitation averages 963.2 Millimeters. Benton 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 | -10.3 °C | 0.2 °C | 21.08 mm |
| February | -7.9 °C | 3.1 °C | 32.51 mm |
| March | -1.9 °C | 10.1 °C | 56.13 mm |
| April | 3.9 °C | 16.8 °C | 95 mm |
| May | 10.5 °C | 22.3 °C | 140.21 mm |
| June | 16.1 °C | 27.4 °C | 134.87 mm |
| July | 18.3 °C | 29.8 °C | 115.06 mm |
| August | 17 °C | 28.9 °C | 109.73 mm |
| September | 11.9 °C | 25.1 °C | 93.73 mm |
| October | 5.1 °C | 18.3 °C | 76.96 mm |
| November | -1.5 °C | 9.8 °C | 52.58 mm |
| December | -7.2 °C | 2.9 °C | 35.31 mm |
| Annual | 4.5 °C | 16.2 °C | 963.17 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 |