Calamus, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.8 °F (low) to 59.4 °F (high). Annual precipitation averages 38.8 Inches. 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 | 13.0 °F | 29.4 °F | 1.3 in. |
| February | 16.6 °F | 33.9 °F | 1.54 in. |
| March | 27.5 °F | 46.9 °F | 2.44 in. |
| April | 38.7 °F | 60.6 °F | 3.89 in. |
| May | 50.6 °F | 71.8 °F | 4.77 in. |
| June | 60.7 °F | 81.1 °F | 4.97 in. |
| July | 64.1 °F | 84.1 °F | 4.33 in. |
| August | 61.9 °F | 82.3 °F | 4.55 in. |
| September | 53.4 °F | 76.5 °F | 3.98 in. |
| October | 41.7 °F | 63.5 °F | 3.09 in. |
| November | 29.7 °F | 48.1 °F | 2.19 in. |
| December | 19.3 °F | 35.0 °F | 1.79 in. |
| Annual | 39.8 °F | 59.4 °F | 38.84 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |