Newmarket, Ontario climate data is summarized below. Average annual temperatures range from 2.9 °C (low) to 12.4 °C (high). Annual precipitation averages 824 Millimeters. Newmarket 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.92 °C | -2.25 °C | 12 mm |
| February | -10.94 °C | -2.67 °C | 4 mm |
| March | -5.07 °C | 4.07 °C | 48 mm |
| April | 1.49 °C | 11.85 °C | 73 mm |
| May | 7.65 °C | 19.37 °C | 106 mm |
| June | 12.71 °C | 23.95 °C | 104 mm |
| July | 15.36 °C | 26.52 °C | 130 mm |
| August | 14.71 °C | 25.52 °C | 126 mm |
| September | 10.37 °C | 21.07 °C | 71 mm |
| October | 5.24 °C | 13.87 °C | 65 mm |
| November | -0.51 °C | 7.21 °C | 50 mm |
| December | -5.89 °C | 0.5 °C | 35 mm |
| Annual | 2.9 °C | 12.4 °C | 824 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 |