Rockwell, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 36.3 °F (low) to 56.1 °F (high). Annual precipitation averages 36.5 Inches. Rockwell is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.9 °F | 24.7 °F | 0.94 in. |
| February | 11.9 °F | 29.3 °F | 1.09 in. |
| March | 23.9 °F | 42.0 °F | 1.99 in. |
| April | 35.4 °F | 57.2 °F | 3.92 in. |
| May | 47.8 °F | 69.4 °F | 5.17 in. |
| June | 58.5 °F | 79.3 °F | 5.69 in. |
| July | 61.9 °F | 82.3 °F | 4.54 in. |
| August | 59.1 °F | 80.1 °F | 4.07 in. |
| September | 50.4 °F | 74.1 °F | 3.36 in. |
| October | 38.0 °F | 60.7 °F | 2.58 in. |
| November | 25.7 °F | 44.0 °F | 1.75 in. |
| December | 14.6 °F | 30.4 °F | 1.37 in. |
| Annual | 36.3 °F | 56.1 °F | 36.47 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 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 |