Weather in Saint John

Find out what weather awaits you in Saint John. This section presents current weather reports, forecasts, and useful charts for planning your day.

The climate in Saint John, Canada, can be characterized as moderate, with four distinct seasons. Visitors to the city can expect a real winter with average sub-zero temperatures (January and February are the coldest months with an average temperature of around -4.7°C), while summer brings comfortable warmth suitable for exploring the city, but without sweltering heat (July and August are the warmest, with an average temperature of around 19°C). Spring and autumn serve as picturesque transitional periods, bringing gradual changes in weather conditions and temperatures.

One of the characteristic features of the weather in Saint John is the relatively small amount of precipitation in millimetres monthly (from 2 to 4 mm), yet the number of days with precipitation remains consistently high throughout the year (from 9 to 14 days per month). This may indicate that precipitation, whether rain or snow, is often light and short-lived. Temperature fluctuations between the coldest and warmest months are significant, highlighting the distinct change of seasons in this corner of Canada.

The climate in Saint John is characterized by clearly defined seasons and a significant annual temperature range, extending from winter lows of around -9.0°C to summer warmth in the region of 23.0°C. January and February are traditionally considered the coldest months, when the average air temperature is approximately -4.8°C and -4.6°C respectively, and night-time temperatures regularly drop to -9.0°C. In contrast, the peak of warmth occurs in July and August, with average temperatures of 19.1°C and 19.0°C and daily highs reaching 23.0°C and 22.7°C respectively, making them the most comfortable months for a visit.

The summer period in Saint John, especially in July and August, offers pleasantly warm weather. Daily highs during these months consistently stay in the range of 22.7°C – 23.0°C, creating ideal conditions for exploring the city and its surroundings. Nights bring refreshing coolness, with temperatures dropping on average to 15.2°C – 15.3°C. Such fluctuations between day and night temperatures, amounting to about 7-8°C, are typical for the summer season in Saint John.

Winters in Saint John are quite frosty. January and February are the harshest: night-time temperatures regularly fall to -9.0°C, and daily highs barely reach -0.7°C in January and -0.2°C in February. Diurnal temperature fluctuations in winter are also noticeable, usually amounting to 8-9°C, which emphasizes the palpable cold of winter nights. The transition seasons — spring and autumn — are characterized by a smooth shift in temperatures: in spring, the air gradually warms up from a March average of -0.2°C to +10.7°C in May, and in autumn, it cools down just as smoothly from a September average of +15.7°C to +3.5°C in November.

In Saint John, precipitation falls quite regularly throughout the year, with no clearly defined rainy season or dry period in terms of total volume observed. The total monthly rainfall is low: the highest amount, around 4 mm, falls in January, March, April, October, November, and December. The lowest volume of precipitation, just 2 mm, is recorded in May. This pattern indicates frequent but, as a rule, light precipitation throughout the year.

The winter months, from December to February, are characterized primarily by snowfall, as average air temperatures consistently stay below freezing. January stands out with the highest number of days with precipitation – averaging 14 days. March and November are transitional months: during this time, both snow and rain are possible, or mixed forms thereof, depending on the current temperature.

In the period from April to October, precipitation in Saint John falls predominantly as rain. As mentioned, the "driest" month in terms of precipitation amount is May (2 mm), yet even in this month, there are about 11 days with precipitation. September is distinguished by the fewest number of days with precipitation — on average 9 days, while the volume of falling precipitation is about 3 mm. Summer months, such as June, July, and August, receive approximately 3 mm of precipitation each, distributed over 11-13 days.

When planning a trip to Saint John, it is important to consider the changeable weather and frequent precipitation throughout the year. The key principle when packing your suitcase should be layering. Indispensable items will include a waterproof and windproof jacket, as well as comfortable waterproof shoes for walking, since the number of days with precipitation is significant in any season. Don't forget an umbrella – it will be useful in both summer rain and the wet snow of the transition seasons.

In winter (from December to March), it is cold in Saint John, with average temperatures dropping below freezing, so you will need very warm clothes: a down jacket or insulated parka, thermal underwear, wool sweaters, a hat, a scarf, and gloves. In spring (April-May) and autumn (September-November), the weather is changeable: days can be either cool or moderately warm. Take a mid-season jacket, a fleece top, jumpers, and several t-shirts to combine clothing depending on the temperature. In summer (June-August), the weather becomes warmer, with average temperatures around 15-19°C. For this period, t-shirts, light trousers, or shorts are suitable, but don't forget to grab a light jacket or sweater for cool evenings and rainy days. Sunscreen and sunglasses will also be useful on clear summer days.

Regardless of the season, comfortable footwear is recommended for exploring the city and its surroundings. Given that even in the summer months the number of days with precipitation remains high (11-13 days), a light waterproof jacket or raincoat will become your faithful companions. An electrical adapter may also be needed if your devices have a different plug type.