Rockwell City, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.2 °F (low) to 57.5 °F (high). Annual precipitation averages 33.1 Inches. Rockwell 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 9.0 °F | 26.5 °F | 0.76 in. |
| February | 13.0 °F | 31.0 °F | 0.99 in. |
| March | 25.0 °F | 44.9 °F | 1.94 in. |
| April | 35.9 °F | 59.2 °F | 3.61 in. |
| May | 48.6 °F | 70.1 °F | 4.92 in. |
| June | 59.6 °F | 80.2 °F | 5.15 in. |
| July | 63.0 °F | 83.1 °F | 3.6 in. |
| August | 60.4 °F | 80.8 °F | 4.02 in. |
| September | 51.3 °F | 75.1 °F | 2.94 in. |
| October | 38.8 °F | 62.1 °F | 2.46 in. |
| November | 26.0 °F | 45.5 °F | 1.41 in. |
| December | 15.2 °F | 31.8 °F | 1.32 in. |
| Annual | 37.2 °F | 57.5 °F | 33.12 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 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 |