Mentor, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.3 °F (low) to 49.3 °F (high). Annual precipitation averages 24.4 Inches. Mentor 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 | -3.0 °F | 15.0 °F | 0.69 in. |
| February | -0.2 °F | 19.6 °F | 0.64 in. |
| March | 14.3 °F | 33.5 °F | 0.92 in. |
| April | 29.4 °F | 50.4 °F | 1.35 in. |
| May | 42.4 °F | 64.8 °F | 3.13 in. |
| June | 53.6 °F | 74.0 °F | 4.24 in. |
| July | 57.0 °F | 78.4 °F | 3.42 in. |
| August | 54.5 °F | 77.8 °F | 3.1 in. |
| September | 45.6 °F | 68.7 °F | 2.95 in. |
| October | 33.5 °F | 53.0 °F | 2.22 in. |
| November | 19.2 °F | 35.3 °F | 0.9 in. |
| December | 5.0 °F | 21.2 °F | 0.86 in. |
| Annual | 29.3 °F | 49.3 °F | 24.42 in. |
| 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 : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |