Waterloo, Ontario climate data is summarized below. Average annual temperatures range from 2.6 °C (low) to 11.9 °C (high). Annual precipitation averages 740 Millimeters. Waterloo 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 | -9.82 °C | -2.8 °C | 7 mm |
| February | -11.27 °C | -3.18 °C | 4 mm |
| March | -5.21 °C | 4.02 °C | 36 mm |
| April | 0.99 °C | 11.49 °C | 60 mm |
| May | 7.37 °C | 18.66 °C | 88 mm |
| June | 12.27 °C | 23.21 °C | 99 mm |
| July | 14.45 °C | 25.41 °C | 128 mm |
| August | 13.82 °C | 24.47 °C | 120 mm |
| September | 9.87 °C | 20.39 °C | 81 mm |
| October | 4.82 °C | 13.58 °C | 58 mm |
| November | -0.82 °C | 6.77 °C | 34 mm |
| December | -5.63 °C | 0.24 °C | 25 mm |
| Annual | 2.6 °C | 11.9 °C | 740 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |