Callender, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.2 °F (low) to 57.6 °F (high). Annual precipitation averages 35.2 Inches. 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 | 9.2 °F | 26.7 °F | 0.87 in. |
| February | 13.2 °F | 31.1 °F | 1.13 in. |
| March | 25.0 °F | 44.6 °F | 2.01 in. |
| April | 36.1 °F | 59.2 °F | 3.73 in. |
| May | 48.7 °F | 70.3 °F | 5.0 in. |
| June | 59.6 °F | 80.2 °F | 5.28 in. |
| July | 63.0 °F | 83.2 °F | 4.1 in. |
| August | 60.3 °F | 80.9 °F | 4.42 in. |
| September | 51.2 °F | 75.0 °F | 3.14 in. |
| October | 38.8 °F | 62.1 °F | 2.56 in. |
| November | 26.2 °F | 45.6 °F | 1.65 in. |
| December | 15.4 °F | 32.0 °F | 1.32 in. |
| Annual | 37.2 °F | 57.6 °F | 35.21 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |