Granville, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.2 °C (low) to 13.9 °C (high). Annual precipitation averages 758.9 Millimeters. Granville 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 | -13.6 °C | -3.4 °C | 18.54 mm |
| February | -11.2 °C | -0.8 °C | 21.84 mm |
| March | -4.8 °C | 6.4 °C | 43.43 mm |
| April | 1.4 °C | 14.5 °C | 80.52 mm |
| May | 8.7 °C | 21.2 °C | 102.87 mm |
| June | 14.7 °C | 26.7 °C | 113.79 mm |
| July | 16.7 °C | 28.5 °C | 87.63 mm |
| August | 15.3 °C | 27.2 °C | 91.44 mm |
| September | 10.3 °C | 23.8 °C | 80.52 mm |
| October | 3.2 °C | 16.3 °C | 59.18 mm |
| November | -4.2 °C | 7 °C | 35.05 mm |
| December | -10.3 °C | -0.7 °C | 24.13 mm |
| Annual | 2.2 °C | 13.9 °C | 758.94 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°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 |