Finlayson, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.8 °C (low) to 11.1 °C (high). Annual precipitation averages 809.5 Millimeters. Finlayson 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 | -6.5 °C | 20.07 mm |
| February | -15.6 °C | -3.4 °C | 21.59 mm |
| March | -8.6 °C | 3.4 °C | 38.86 mm |
| April | -1.3 °C | 11.3 °C | 67.82 mm |
| May | 5.3 °C | 18.9 °C | 92.71 mm |
| June | 10.8 °C | 23.9 °C | 113.79 mm |
| July | 13.7 °C | 26.5 °C | 117.35 mm |
| August | 12.4 °C | 25.4 °C | 102.87 mm |
| September | 7.8 °C | 20.9 °C | 86.11 mm |
| October | 1.4 °C | 12.9 °C | 77.22 mm |
| November | -5.4 °C | 3.8 °C | 41.15 mm |
| December | -12.8 °C | -3.6 °C | 29.97 mm |
| Annual | -0.8 °C | 11.1 °C | 809.51 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 |