Callender, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.9 °C (low) to 14.2 °C (high). Annual precipitation averages 894.3 Millimeters. Callender 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 | -12.7 °C | -2.9 °C | 22.1 mm |
| February | -10.4 °C | -0.5 °C | 28.7 mm |
| March | -3.9 °C | 7 °C | 51.05 mm |
| April | 2.3 °C | 15.1 °C | 94.74 mm |
| May | 9.3 °C | 21.3 °C | 127 mm |
| June | 15.3 °C | 26.8 °C | 134.11 mm |
| July | 17.2 °C | 28.4 °C | 104.14 mm |
| August | 15.7 °C | 27.2 °C | 112.27 mm |
| September | 10.7 °C | 23.9 °C | 79.76 mm |
| October | 3.8 °C | 16.7 °C | 65.02 mm |
| November | -3.2 °C | 7.6 °C | 41.91 mm |
| December | -9.2 °C | 0 °C | 33.53 mm |
| Annual | 2.9 °C | 14.2 °C | 894.33 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 | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |