Graf, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.5 °F (low) to 57.3 °F (high). Annual precipitation averages 38.9 Inches. 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 | 10.3 °F | 26.9 °F | 1.27 in. |
| February | 13.7 °F | 31.4 °F | 1.45 in. |
| March | 25.4 °F | 44.4 °F | 2.11 in. |
| April | 36.5 °F | 58.2 °F | 3.85 in. |
| May | 48.2 °F | 69.9 °F | 4.62 in. |
| June | 58.7 °F | 79.4 °F | 5.87 in. |
| July | 62.2 °F | 82.6 °F | 4.82 in. |
| August | 60.0 °F | 80.8 °F | 4.16 in. |
| September | 51.2 °F | 74.1 °F | 3.87 in. |
| October | 39.4 °F | 61.1 °F | 2.92 in. |
| November | 27.8 °F | 45.5 °F | 2.28 in. |
| December | 17.0 °F | 32.7 °F | 1.7 in. |
| Annual | 37.5 °F | 57.3 °F | 38.92 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |