Sigourney, 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 15.5 °C (high). Annual precipitation averages 965.7 Millimeters. Sigourney 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 | -10.6 °C | -1 °C | 30.23 mm |
| February | -8.5 °C | 1.6 °C | 37.85 mm |
| March | -2.5 °C | 8.8 °C | 57.66 mm |
| April | 3.7 °C | 16.2 °C | 98.3 mm |
| May | 10.4 °C | 21.9 °C | 128.02 mm |
| June | 16.2 °C | 27.3 °C | 138.94 mm |
| July | 17.9 °C | 29.4 °C | 105.41 mm |
| August | 16.7 °C | 28.4 °C | 111.76 mm |
| September | 11.7 °C | 24.7 °C | 92.96 mm |
| October | 4.9 °C | 17.7 °C | 68.83 mm |
| November | -1.4 °C | 9.1 °C | 56.13 mm |
| December | -7.2 °C | 2 °C | 39.62 mm |
| Annual | 4.3 °C | 15.5 °C | 965.71 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |