Green Bay, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.7 °C (low) to 12.2 °C (high). Annual precipitation averages 828.6 Millimeters. Green Bay is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.3 °C | -3.6 °C | 39.37 mm |
| February | -11.6 °C | -1.8 °C | 30.48 mm |
| March | -6.1 °C | 4.1 °C | 46.74 mm |
| April | 0.2 °C | 11.4 °C | 82.3 mm |
| May | 6.6 °C | 18.7 °C | 95.5 mm |
| June | 12.1 °C | 23.9 °C | 103.63 mm |
| July | 14.8 °C | 26.6 °C | 93.22 mm |
| August | 14.1 °C | 25.6 °C | 86.87 mm |
| September | 9.6 °C | 21.7 °C | 84.84 mm |
| October | 3.4 °C | 14.2 °C | 71.37 mm |
| November | -2.5 °C | 6.3 °C | 49.28 mm |
| December | -8.4 °C | -0.4 °C | 44.96 mm |
| Annual | 1.7 °C | 12.2 °C | 828.56 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |