Forest City, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 35.7 °F (low) to 55.5 °F (high). Annual precipitation averages 34.1 Inches. 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 | 6.9 °F | 23.8 °F | 0.98 in. |
| February | 11.0 °F | 28.5 °F | 0.93 in. |
| March | 23.5 °F | 41.1 °F | 1.93 in. |
| April | 34.9 °F | 56.5 °F | 3.68 in. |
| May | 47.4 °F | 69.0 °F | 4.8 in. |
| June | 58.2 °F | 78.9 °F | 5.35 in. |
| July | 61.5 °F | 81.8 °F | 4.36 in. |
| August | 58.7 °F | 79.5 °F | 3.82 in. |
| September | 49.9 °F | 73.4 °F | 3.14 in. |
| October | 37.3 °F | 60.2 °F | 2.28 in. |
| November | 25.2 °F | 43.3 °F | 1.52 in. |
| December | 13.7 °F | 29.6 °F | 1.28 in. |
| Annual | 35.7 °F | 55.5 °F | 34.07 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |