Polk City, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.2 °C (low) to 15.5 °C (high). Annual precipitation averages 907.3 Millimeters. Polk City 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 | -11 °C | -1.3 °C | 25.15 mm |
| February | -8.8 °C | 1.3 °C | 32.51 mm |
| March | -2.6 °C | 8.5 °C | 53.09 mm |
| April | 3.7 °C | 16.4 °C | 95 mm |
| May | 10.3 °C | 22.1 °C | 123.44 mm |
| June | 15.9 °C | 27.4 °C | 130.3 mm |
| July | 18.2 °C | 29.6 °C | 106.17 mm |
| August | 16.8 °C | 28.5 °C | 104.14 mm |
| September | 11.9 °C | 25.1 °C | 87.88 mm |
| October | 5.1 °C | 17.6 °C | 64.77 mm |
| November | -1.7 °C | 9.1 °C | 47.5 mm |
| December | -7.7 °C | 1.7 °C | 37.34 mm |
| Annual | 4.2 °C | 15.5 °C | 907.29 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |