Carter Lake, 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 16.6 °C (high). Annual precipitation averages 836.7 Millimeters. Carter Lake is located in USDA Plant Hardiness Zone 6a. 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 | -10.4 °C | 0.2 °C | 20.83 mm |
| February | -8.3 °C | 3 °C | 26.16 mm |
| March | -2.3 °C | 10.2 °C | 45.47 mm |
| April | 3.8 °C | 17.3 °C | 86.87 mm |
| May | 10.7 °C | 22.9 °C | 126.49 mm |
| June | 16.7 °C | 28.5 °C | 119.63 mm |
| July | 19 °C | 30.4 °C | 90.68 mm |
| August | 17.5 °C | 29.4 °C | 103.89 mm |
| September | 12.2 °C | 25.8 °C | 79.25 mm |
| October | 5.1 °C | 18.6 °C | 65.79 mm |
| November | -2 °C | 9.8 °C | 37.59 mm |
| December | -7.6 °C | 2.7 °C | 34.04 mm |
| Annual | 4.5 °C | 16.6 °C | 836.69 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 6a : -23.3°C to -20.6°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 |