Saint John, New Brunswick climate data is summarized below. Average annual temperatures range from 36 °F (low) to 50.7 °F (high). Annual precipitation averages 35.7 Inches. 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 | -23.4 °F | -18.7 °F | 711.2 in. |
| February | -23.3 °F | -18.4 °F | 635 in. |
| March | -21.1 °F | -16.4 °F | 1270 in. |
| April | -17.6 °F | -13 °F | 1955.8 in. |
| May | -14.7 °F | -10.2 °F | 2108.2 in. |
| June | -12.2 °F | -7.7 °F | 2794 in. |
| July | -10.5 °F | -6 °F | 2184.4 in. |
| August | -10.4 °F | -5.9 °F | 1854.2 in. |
| September | -12.3 °F | -7.6 °F | 2082.8 in. |
| October | -14.8 °F | -10.3 °F | 2717.8 in. |
| November | -17.5 °F | -13.4 °F | 2743.2 in. |
| December | -20.8 °F | -16.6 °F | 2006.6 in. |
| Annual | 36 °F | 50.7 °F | 35.74 in. |
| 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 : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |