Stewart, British Columbia climate data is summarized below. Average annual temperatures range from -3 °C (low) to 2.4 °C (high). Annual precipitation averages 1398 Millimeters. Stewart is located in USDA Plant Hardiness Zone 6b. 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 | -10.12 °C | -5.5 °C | 20 mm |
| February | -10.15 °C | -4.38 °C | 7 mm |
| March | -9.09 °C | -3.21 °C | 19 mm |
| April | -5.2 °C | 0.51 °C | 52 mm |
| May | -0.26 °C | 6 °C | 136 mm |
| June | 3.39 °C | 9.88 °C | 151 mm |
| July | 5.87 °C | 12.05 °C | 161 mm |
| August | 5.91 °C | 12.34 °C | 209 mm |
| September | 2.59 °C | 7.8 °C | 305 mm |
| October | -1.29 °C | 2.27 °C | 253 mm |
| November | -7.2 °C | -3.34 °C | 67 mm |
| December | -10.17 °C | -5.84 °C | 18 mm |
| Annual | -3 °C | 2.4 °C | 1398 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 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |