De Graff, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.8 °C (low) to 12.2 °C (high). Annual precipitation averages 700.3 Millimeters. De Graff 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 | -16.2 °C | -6.1 °C | 15.49 mm |
| February | -14.3 °C | -3.5 °C | 17.53 mm |
| March | -6.9 °C | 3.5 °C | 34.54 mm |
| April | 0.4 °C | 12.7 °C | 59.69 mm |
| May | 7.7 °C | 20.3 °C | 81.28 mm |
| June | 13.8 °C | 25.7 °C | 112.01 mm |
| July | 15.9 °C | 27.8 °C | 104.9 mm |
| August | 14.3 °C | 26.7 °C | 97.54 mm |
| September | 9.6 °C | 22.9 °C | 67.82 mm |
| October | 2.2 °C | 14.6 °C | 60.2 mm |
| November | -5.2 °C | 5 °C | 29.21 mm |
| December | -12.2 °C | -2.9 °C | 20.07 mm |
| Annual | 0.8 °C | 12.2 °C | 700.28 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 | Dfb - Humid Continental Mild Summer, Wet All Year |