Whitby, Ontario climate data is summarized below. Average annual temperatures range from 4 °C (low) to 13.1 °C (high). Annual precipitation averages 933 Millimeters. Whitby 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 | -8.46 °C | -0.98 °C | 22 mm |
| February | -9.57 °C | -1.35 °C | 21 mm |
| March | -3.93 °C | 5 °C | 68 mm |
| April | 2.42 °C | 12.29 °C | 103 mm |
| May | 8.47 °C | 19.3 °C | 97 mm |
| June | 13.57 °C | 24.02 °C | 114 mm |
| July | 16.19 °C | 26.87 °C | 106 mm |
| August | 15.66 °C | 26.05 °C | 104 mm |
| September | 11.29 °C | 21.68 °C | 73 mm |
| October | 6.03 °C | 14.63 °C | 93 mm |
| November | 0.3 °C | 8.16 °C | 69 mm |
| December | -4.63 °C | 1.68 °C | 63 mm |
| Annual | 4 °C | 13.1 °C | 933 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 |