Cass Lake, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.6 °F (low) to 50.3 °F (high). Annual precipitation averages 26 Inches. 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 | -2.1 °F | 17.8 °F | 0.67 in. |
| February | 0.4 °F | 23.7 °F | 0.66 in. |
| March | 14.3 °F | 36.7 °F | 1.09 in. |
| April | 28.5 °F | 51.0 °F | 1.89 in. |
| May | 41.6 °F | 64.8 °F | 2.9 in. |
| June | 52.5 °F | 74.1 °F | 4.08 in. |
| July | 57.2 °F | 78.7 °F | 4.0 in. |
| August | 54.9 °F | 77.0 °F | 3.04 in. |
| September | 46.5 °F | 67.9 °F | 2.96 in. |
| October | 34.1 °F | 52.5 °F | 2.63 in. |
| November | 21.0 °F | 36.1 °F | 1.11 in. |
| December | 6.3 °F | 22.9 °F | 0.92 in. |
| Annual | 29.6 °F | 50.3 °F | 25.95 in. |
| 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 : -35°F to -30°F |
| Plant Hardiness Zone - 2012 | Zone 3a : -40°F to -35°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |