Rockwell, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.4 °C (low) to 13.4 °C (high). Annual precipitation averages 926.4 Millimeters. 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 | -13.4 °C | -4.1 °C | 23.88 mm |
| February | -11.2 °C | -1.5 °C | 27.69 mm |
| March | -4.5 °C | 5.6 °C | 50.55 mm |
| April | 1.9 °C | 14 °C | 99.57 mm |
| May | 8.8 °C | 20.8 °C | 131.32 mm |
| June | 14.7 °C | 26.3 °C | 144.53 mm |
| July | 16.6 °C | 27.9 °C | 115.32 mm |
| August | 15.1 °C | 26.7 °C | 103.38 mm |
| September | 10.2 °C | 23.4 °C | 85.34 mm |
| October | 3.3 °C | 15.9 °C | 65.53 mm |
| November | -3.5 °C | 6.7 °C | 44.45 mm |
| December | -9.7 °C | -0.9 °C | 34.8 mm |
| Annual | 2.4 °C | 13.4 °C | 926.36 mm |
| 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 : -28.9°C to -26.1°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 |