Forest City, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2 °C (low) to 13.1 °C (high). Annual precipitation averages 865.4 Millimeters. Forest City is located in USDA Plant Hardiness Zone 5a. 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 | -13.9 °C | -4.6 °C | 24.89 mm |
| February | -11.7 °C | -1.9 °C | 23.62 mm |
| March | -4.7 °C | 5.1 °C | 49.02 mm |
| April | 1.6 °C | 13.6 °C | 93.47 mm |
| May | 8.6 °C | 20.6 °C | 121.92 mm |
| June | 14.6 °C | 26.1 °C | 135.89 mm |
| July | 16.4 °C | 27.7 °C | 110.74 mm |
| August | 14.8 °C | 26.4 °C | 97.03 mm |
| September | 9.9 °C | 23 °C | 79.76 mm |
| October | 2.9 °C | 15.7 °C | 57.91 mm |
| November | -3.8 °C | 6.3 °C | 38.61 mm |
| December | -10.2 °C | -1.3 °C | 32.51 mm |
| Annual | 2 °C | 13.1 °C | 865.37 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |