Saint John, New Brunswick climate data is summarized below. Average annual temperatures range from 2.2 °C (low) to 10.4 °C (high). Annual precipitation averages 908 Millimeters. Saint John is located in USDA Plant Hardiness Zone 5b. 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 | -10.14 °C | -1.58 °C | 28 mm |
| February | -9.93 °C | -1.19 °C | 25 mm |
| March | -5.92 °C | 2.56 °C | 50 mm |
| April | 0.34 °C | 8.61 °C | 77 mm |
| May | 5.51 °C | 13.7 °C | 83 mm |
| June | 9.96 °C | 18.14 °C | 110 mm |
| July | 13.13 °C | 21.23 °C | 86 mm |
| August | 13.3 °C | 21.46 °C | 73 mm |
| September | 9.85 °C | 18.3 °C | 82 mm |
| October | 5.28 °C | 13.39 °C | 107 mm |
| November | 0.56 °C | 7.94 °C | 108 mm |
| December | -5.37 °C | 2.16 °C | 79 mm |
| Annual | 2.2 °C | 10.4 °C | 908 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 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |