Mattawa, Ontario climate data is summarized below. Average annual temperatures range from -0.1 °C (low) to 10.6 °C (high). Annual precipitation averages 652 Millimeters. Mattawa 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 | -16.21 °C | -6.21 °C | 0 mm |
| February | -16.63 °C | -5.39 °C | 0 mm |
| March | -9.51 °C | 1.32 °C | 16 mm |
| April | -1.54 °C | 9.94 °C | 60 mm |
| May | 6 °C | 19.01 °C | 71 mm |
| June | 11.48 °C | 23.62 °C | 82 mm |
| July | 13.89 °C | 25.64 °C | 99 mm |
| August | 13.46 °C | 24.74 °C | 100 mm |
| September | 8.59 °C | 20.07 °C | 90 mm |
| October | 3.39 °C | 12.5 °C | 94 mm |
| November | -2.87 °C | 5.06 °C | 40 mm |
| December | -11.7 °C | -3.33 °C | 0 mm |
| Annual | -0.1 °C | 10.6 °C | 652 mm |
| 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 : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |