Graf, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.1 °C (low) to 14 °C (high). Annual precipitation averages 988.6 Millimeters. Graf 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.1 °C | -2.8 °C | 32.26 mm |
| February | -10.2 °C | -0.3 °C | 36.83 mm |
| March | -3.7 °C | 6.9 °C | 53.59 mm |
| April | 2.5 °C | 14.6 °C | 97.79 mm |
| May | 9 °C | 21.1 °C | 117.35 mm |
| June | 14.8 °C | 26.3 °C | 149.1 mm |
| July | 16.8 °C | 28.1 °C | 122.43 mm |
| August | 15.6 °C | 27.1 °C | 105.66 mm |
| September | 10.7 °C | 23.4 °C | 98.3 mm |
| October | 4.1 °C | 16.2 °C | 74.17 mm |
| November | -2.3 °C | 7.5 °C | 57.91 mm |
| December | -8.3 °C | 0.4 °C | 43.18 mm |
| Annual | 3.1 °C | 14 °C | 988.57 mm |
| 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 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 |