Clarion, 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 13.7 °C (high). Annual precipitation averages 893.6 Millimeters. Clarion 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -13.3 °C | -3.8 °C | 20.32 mm |
| February | -11.1 °C | -1.3 °C | 24.13 mm |
| March | -4.4 °C | 5.8 °C | 51.05 mm |
| April | 1.8 °C | 14.3 °C | 98.55 mm |
| May | 8.9 °C | 21 °C | 129.03 mm |
| June | 14.9 °C | 26.7 °C | 142.49 mm |
| July | 16.7 °C | 28.1 °C | 111.51 mm |
| August | 15.1 °C | 26.9 °C | 104.65 mm |
| September | 10 °C | 23.8 °C | 80.52 mm |
| October | 3.1 °C | 16.2 °C | 57.66 mm |
| November | -3.6 °C | 7 °C | 43.18 mm |
| December | -9.8 °C | -0.7 °C | 30.48 mm |
| Annual | 2.4 °C | 13.7 °C | 893.57 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 |