Grand Marsh, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.5 °C (low) to 13.1 °C (high). Annual precipitation averages 905.3 Millimeters. Grand Marsh is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -13.9 °C | -3.6 °C | 34.04 mm |
| February | -12.2 °C | -1.1 °C | 30.73 mm |
| March | -6 °C | 5.7 °C | 48.51 mm |
| April | 0.5 °C | 13.3 °C | 92.2 mm |
| May | 7.5 °C | 20.2 °C | 105.92 mm |
| June | 13.1 °C | 25.3 °C | 127 mm |
| July | 15.2 °C | 27.8 °C | 112.01 mm |
| August | 14.1 °C | 26.3 °C | 106.68 mm |
| September | 9.5 °C | 22.3 °C | 89.15 mm |
| October | 2.9 °C | 14.8 °C | 68.58 mm |
| November | -3.4 °C | 6.4 °C | 49.28 mm |
| December | -9.7 °C | -0.7 °C | 41.15 mm |
| Annual | 1.5 °C | 13.1 °C | 905.25 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |