Rowan, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.2 °C (low) to 13.5 °C (high). Annual precipitation averages 908.6 Millimeters. Rowan 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 | -3.9 °C | 21.59 mm |
| February | -11.3 °C | -1.3 °C | 25.4 mm |
| March | -4.6 °C | 5.8 °C | 51.56 mm |
| April | 1.7 °C | 14.1 °C | 97.54 mm |
| May | 8.9 °C | 20.8 °C | 128.52 mm |
| June | 14.8 °C | 26.4 °C | 144.78 mm |
| July | 16.6 °C | 27.9 °C | 112.27 mm |
| August | 14.8 °C | 26.7 °C | 106.68 mm |
| September | 9.8 °C | 23.6 °C | 81.53 mm |
| October | 3 °C | 16.1 °C | 61.72 mm |
| November | -3.6 °C | 6.8 °C | 43.69 mm |
| December | -9.8 °C | -0.8 °C | 33.27 mm |
| Annual | 2.2 °C | 13.5 °C | 908.55 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |