Cass Lake, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.3 °C (low) to 10.1 °C (high). Annual precipitation averages 659.1 Millimeters. Cass Lake is located in USDA Plant Hardiness Zone 3b. 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 | -18.9 °C | -7.9 °C | 17.02 mm |
| February | -17.6 °C | -4.6 °C | 16.76 mm |
| March | -9.8 °C | 2.6 °C | 27.69 mm |
| April | -1.9 °C | 10.6 °C | 48.01 mm |
| May | 5.3 °C | 18.2 °C | 73.66 mm |
| June | 11.4 °C | 23.4 °C | 103.63 mm |
| July | 14 °C | 25.9 °C | 101.6 mm |
| August | 12.7 °C | 25 °C | 77.22 mm |
| September | 8.1 °C | 19.9 °C | 75.18 mm |
| October | 1.2 °C | 11.4 °C | 66.8 mm |
| November | -6.1 °C | 2.3 °C | 28.19 mm |
| December | -14.3 °C | -5.1 °C | 23.37 mm |
| Annual | -1.3 °C | 10.1 °C | 659.13 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 3b : -37.2°C to -34.4°C |
| Plant Hardiness Zone - 2012 | Zone 3a : -40°C to -37.2°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |