Waterloo, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.1 °C (low) to 13.8 °C (high). Annual precipitation averages 942.1 Millimeters. Waterloo is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.5 °C | -2.7 °C | 38.1 mm |
| February | -9.9 °C | -0.6 °C | 39.12 mm |
| March | -4.1 °C | 6.1 °C | 50.8 mm |
| April | 2.2 °C | 13.8 °C | 96.77 mm |
| May | 8.7 °C | 20.7 °C | 104.9 mm |
| June | 14.3 °C | 26.1 °C | 136.14 mm |
| July | 16.6 °C | 28.1 °C | 105.66 mm |
| August | 15.5 °C | 27 °C | 104.9 mm |
| September | 10.9 °C | 23.3 °C | 90.17 mm |
| October | 4.4 °C | 15.8 °C | 75.95 mm |
| November | -1.7 °C | 7.5 °C | 55.37 mm |
| December | -7.7 °C | 0.3 °C | 44.2 mm |
| Annual | 3.1 °C | 13.8 °C | 942.08 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |