Sibley, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 1.6 °C (low) to 13.1 °C (high). Annual precipitation averages 767.3 Millimeters. Sibley is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14.3 °C | -4.4 °C | 18.8 mm |
| February | -12 °C | -1.9 °C | 21.59 mm |
| March | -5.7 °C | 5.1 °C | 40.39 mm |
| April | 0.9 °C | 13.7 °C | 80.26 mm |
| May | 8.1 °C | 20.6 °C | 102.87 mm |
| June | 14.4 °C | 26.3 °C | 122.68 mm |
| July | 16.4 °C | 28.1 °C | 87.38 mm |
| August | 14.9 °C | 26.8 °C | 87.12 mm |
| September | 9.9 °C | 23.3 °C | 84.33 mm |
| October | 2.7 °C | 15.6 °C | 60.45 mm |
| November | -4.7 °C | 6.1 °C | 36.07 mm |
| December | -11.1 °C | -1.8 °C | 25.4 mm |
| Annual | 1.6 °C | 13.1 °C | 767.34 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |