Oshawa, Ontario climate data is summarized below. Average annual temperatures range from 3.5 °C (low) to 13 °C (high). Annual precipitation averages 950 Millimeters. Oshawa is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.89 °C | -1.2 °C | 22 mm |
| February | -10.06 °C | -1.58 °C | 20 mm |
| March | -4.44 °C | 4.83 °C | 68 mm |
| April | 2.16 °C | 12.38 °C | 105 mm |
| May | 8.23 °C | 19.51 °C | 99 mm |
| June | 13.27 °C | 24.16 °C | 119 mm |
| July | 15.79 °C | 26.89 °C | 107 mm |
| August | 15.19 °C | 26.02 °C | 108 mm |
| September | 10.81 °C | 21.59 °C | 73 mm |
| October | 5.6 °C | 14.46 °C | 92 mm |
| November | -0.14 °C | 7.96 °C | 72 mm |
| December | -5.1 °C | 1.39 °C | 65 mm |
| Annual | 3.5 °C | 13 °C | 950 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |