Tonka Bay, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.3 °C (low) to 12.6 °C (high). Annual precipitation averages 809 Millimeters. Tonka Bay is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14.4 °C | -5.1 °C | 22.1 mm |
| February | -12.6 °C | -2.5 °C | 22.61 mm |
| March | -5.6 °C | 4.5 °C | 39.12 mm |
| April | 1.9 °C | 12.9 °C | 70.87 mm |
| May | 9 °C | 20.2 °C | 107.19 mm |
| June | 14.8 °C | 25.5 °C | 118.11 mm |
| July | 17.3 °C | 28.1 °C | 103.89 mm |
| August | 16 °C | 26.8 °C | 110.24 mm |
| September | 11.4 °C | 22.7 °C | 82.8 mm |
| October | 4 °C | 14.6 °C | 61.72 mm |
| November | -3.2 °C | 5.5 °C | 37.59 mm |
| December | -10.6 °C | -2.3 °C | 32.77 mm |
| Annual | 2.3 °C | 12.6 °C | 809.01 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |