Calamus, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.3 °C (low) to 15.2 °C (high). Annual precipitation averages 986.6 Millimeters. Calamus is located in USDA Plant Hardiness Zone 5b. 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 | -10.6 °C | -1.4 °C | 33.02 mm |
| February | -8.6 °C | 1.1 °C | 39.12 mm |
| March | -2.5 °C | 8.3 °C | 61.98 mm |
| April | 3.7 °C | 15.9 °C | 98.81 mm |
| May | 10.3 °C | 22.1 °C | 121.16 mm |
| June | 15.9 °C | 27.3 °C | 126.24 mm |
| July | 17.8 °C | 28.9 °C | 109.98 mm |
| August | 16.6 °C | 27.9 °C | 115.57 mm |
| September | 11.9 °C | 24.7 °C | 101.09 mm |
| October | 5.4 °C | 17.5 °C | 78.49 mm |
| November | -1.3 °C | 8.9 °C | 55.63 mm |
| December | -7.1 °C | 1.7 °C | 45.47 mm |
| Annual | 4.3 °C | 15.2 °C | 986.56 mm |
| 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 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |