Grand Marsh, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 34.7 °F (low) to 55.5 °F (high). Annual precipitation averages 35.6 Inches. 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 | 7.0 °F | 25.5 °F | 1.34 in. |
| February | 10.1 °F | 30.0 °F | 1.21 in. |
| March | 21.2 °F | 42.2 °F | 1.91 in. |
| April | 32.9 °F | 55.9 °F | 3.63 in. |
| May | 45.5 °F | 68.4 °F | 4.17 in. |
| June | 55.6 °F | 77.6 °F | 5.0 in. |
| July | 59.4 °F | 82.0 °F | 4.41 in. |
| August | 57.4 °F | 79.3 °F | 4.2 in. |
| September | 49.1 °F | 72.1 °F | 3.51 in. |
| October | 37.3 °F | 58.6 °F | 2.7 in. |
| November | 25.8 °F | 43.6 °F | 1.94 in. |
| December | 14.6 °F | 30.8 °F | 1.62 in. |
| Annual | 34.7 °F | 55.5 °F | 35.64 in. |
| 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 : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |