Polk City, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.5 °F (low) to 59.9 °F (high). Annual precipitation averages 35.7 Inches. 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 | 12.2 °F | 29.6 °F | 0.99 in. |
| February | 16.2 °F | 34.3 °F | 1.28 in. |
| March | 27.4 °F | 47.3 °F | 2.09 in. |
| April | 38.6 °F | 61.5 °F | 3.74 in. |
| May | 50.5 °F | 71.8 °F | 4.86 in. |
| June | 60.7 °F | 81.3 °F | 5.13 in. |
| July | 64.8 °F | 85.3 °F | 4.18 in. |
| August | 62.2 °F | 83.3 °F | 4.1 in. |
| September | 53.5 °F | 77.2 °F | 3.46 in. |
| October | 41.2 °F | 63.7 °F | 2.55 in. |
| November | 29.0 °F | 48.4 °F | 1.87 in. |
| December | 18.1 °F | 35.0 °F | 1.47 in. |
| Annual | 39.5 °F | 59.9 °F | 35.72 in. |
| 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 : -15°F to -10°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 |