Norwalk, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.6 °C (low) to 12.8 °C (high). Annual precipitation averages 947.4 Millimeters. Norwalk is located in USDA Plant Hardiness Zone 4b. 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 | -13.6 °C | -3.9 °C | 29.97 mm |
| February | -11.9 °C | -1.3 °C | 28.19 mm |
| March | -5.6 °C | 5.4 °C | 46.99 mm |
| April | 1 °C | 13.3 °C | 96.52 mm |
| May | 7.6 °C | 19.9 °C | 121.16 mm |
| June | 13.2 °C | 25.1 °C | 136.14 mm |
| July | 15.3 °C | 27.2 °C | 112.01 mm |
| August | 14.1 °C | 26.1 °C | 115.82 mm |
| September | 9.4 °C | 22 °C | 99.06 mm |
| October | 2.9 °C | 14.7 °C | 72.9 mm |
| November | -3.4 °C | 6.2 °C | 50.04 mm |
| December | -9.6 °C | -0.9 °C | 38.61 mm |
| Annual | 1.6 °C | 12.8 °C | 947.41 mm |
| 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 4b : -31.7°C to -28.9°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 |