Hewitt, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.7 °C (low) to 10.4 °C (high). Annual precipitation averages 688.1 Millimeters. Hewitt is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -18.3 °C | -7.7 °C | 16.51 mm |
| February | -16.4 °C | -4.8 °C | 16.76 mm |
| March | -8.9 °C | 2.2 °C | 30.23 mm |
| April | -1.2 °C | 11.1 °C | 54.1 mm |
| May | 6.2 °C | 18.4 °C | 88.14 mm |
| June | 12.2 °C | 23.3 °C | 109.73 mm |
| July | 14.7 °C | 26 °C | 108.71 mm |
| August | 13.1 °C | 25.2 °C | 77.22 mm |
| September | 8.4 °C | 20.6 °C | 69.6 mm |
| October | 1.3 °C | 12.3 °C | 70.61 mm |
| November | -6.1 °C | 3 °C | 26.42 mm |
| December | -13.6 °C | -4.7 °C | 20.07 mm |
| Annual | -0.7 °C | 10.4 °C | 688.1 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |