Riverton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 16.9 °C (high). Annual precipitation averages 867.9 Millimeters. Riverton 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.1 °C | 0.8 °C | 19.81 mm |
| February | -7.8 °C | 3.7 °C | 27.94 mm |
| March | -1.8 °C | 10.9 °C | 47.24 mm |
| April | 4.1 °C | 17.5 °C | 84.58 mm |
| May | 10.9 °C | 23.2 °C | 138.18 mm |
| June | 16.7 °C | 28.3 °C | 128.52 mm |
| July | 18.8 °C | 30.2 °C | 109.22 mm |
| August | 17.2 °C | 29.3 °C | 90.68 mm |
| September | 12 °C | 25.9 °C | 78.49 mm |
| October | 5.2 °C | 19.2 °C | 69.09 mm |
| November | -1.8 °C | 10.3 °C | 42.42 mm |
| December | -7.2 °C | 3.3 °C | 31.75 mm |
| Annual | 4.7 °C | 16.9 °C | 867.92 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 |