Denham, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.1 °C (low) to 10.5 °C (high). Annual precipitation averages 786.1 Millimeters. Denham is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -17.7 °C | -6.9 °C | 20.32 mm |
| February | -15.8 °C | -3.8 °C | 20.83 mm |
| March | -8.9 °C | 2.9 °C | 36.32 mm |
| April | -1.7 °C | 10.4 °C | 62.23 mm |
| May | 4.6 °C | 18.1 °C | 87.63 mm |
| June | 9.9 °C | 23.2 °C | 116.59 mm |
| July | 13.1 °C | 25.9 °C | 114.81 mm |
| August | 12.2 °C | 24.8 °C | 99.57 mm |
| September | 7.9 °C | 20.2 °C | 81.79 mm |
| October | 1.5 °C | 12.1 °C | 76.71 mm |
| November | -5.5 °C | 3.2 °C | 40.13 mm |
| December | -13 °C | -4.2 °C | 29.21 mm |
| Annual | -1.1 °C | 10.5 °C | 786.14 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |