Environment Canada - Atlantic Climate Centre

No part of New Brunswick lies more than 200 km from the ocean, yet the province has a typically continental flavour to its climate. During the winter, cold air, largely unaltered, frequently flows across New Brunswick from the centre of North America, and most storms affecting the province originate either over the North Pacific or the Gulf of Mexico. In summer, the predominant air mass is warm continental, with occasional incursions of hot, humid air from the Gulf of Mexico. On the other hand, influxes of moist Atlantic air produce mild spells in winter and periods of cool weather in summer.

Northwestern and central New Brunswick are the parts of the province that are least affected by the ocean. The north and east shores are modified by the Gulf of St. Lawrence, but less so than their proximity might suggest. The extent of the sea-effect depends to a large degree on the wind direction, with onshore winds causing the most moderation. The cold Gulf waters retard warming of the air in spring, keep the summer maximum temperature low, and provide a slight warming of the air in fall--provided the winds are off the water. Near the Bay of Fundy, continental air masses are modified by the ocean. Coastal locations such as St. Andrews and Saint John experience moist Atlantic air most of the year, producing mild periods during the winter and cool weather the rest of the year.

Yet, in spite of their by-the-sea location, New Brunswick coastal areas are not good examples of true marine climates. Continental climates, compared with true maritime climates, have an earlier spring and shorter fall, wider fluctuations of temperature from day to day and from season to season, and more snowfall but less total precipitation. Near the coast there is a blending of these continental and maritime influences, with the temperature moderating effect of the ocean increasing the closer we get to the coast.

There are two key indicators that tell us whether a climate is influenced more by the ocean or by the land in northern latitudes. The first is the season of maximum precipitation: in marine climates it is the cold season. The second is the percentage of the total annual precipitation that falls as snow: less than 25% for marine areas. Saint John's climate qualifies as marine on both counts.

The Land

The southern landscape is characterized by hills sloping down to tidal marshes at the edge of the Bay of Fundy, whereas the eastern and central portions of the province consist of rolling hills cut by river valleys. The highlands in the northwest are an extension of the Appalachian mountain chain. Mount Carleton, the highest point in the Maritimes, is found here. At 820 m above sea level, however, its elevation is still 240 m lower than Calgary's.

Apart from local effects and an influence on the direction of air motion, topography has little influence on New Brunswick's climate.

Temperature: A Province of Contrasts

January is the coldest month in New Brunswick and July is the warmest. Along the Fundy coast, average daytime highs vary between 20 and 22C in the summer. These temperatures are reached fairly early in the day, by 11 a.m. or noon, before the sea breeze sets in and causes them to drop sharply. The sea breeze is not as prevalent along the Gulf coast, however, partly because the Gulf tides are not as pronounced as the Bay of Fundy's. Also, as the warm season progresses, the shallow waters of the Gulf heat up faster and reach higher temperatures than those of Fundy, thus diminishing the difference between air and water temperatures. Since it is precisely this difference which creates the sea breeze, the strength of the breezes off the Gulf are decreased.

As we move inland, the moderating effect of the ocean diminishes, and the interior regularly experiences temperatures of 25C and higher during the summer. Along the Gulf of St. Lawrence, afternoon temperatures regularly reach 24C, except on those days when the cool sea breeze prevails. On several occasions, extremes in New Brunswick have exceeded 37.8C (100F). The highest temperature ever recorded in the province is 39.4C, set at Nepisiguit Falls, Rexton, and Woodstock on August 18 and 19, 1935.

In winter, temperatures decrease noticeably from south to north. The interior,which has elevations above 600 m and is more directly in the path of continental air masses, experiences very cold winters. At Edmundston, the January mean temperature is -12.2C. As we move south, however, this coldness is gradually tempered by the effects of latitude and, to a greater extent, the sea. Along the south-eastern shores, the January mean is around -7.5C.

Frigid temperatures are not infrequent, with most settlements in the north-west reporting extreme low temperatures of -30 to -35C every winter. The all-time provincial low is -47.2C, recorded at Sisson Dam, a weather station near Plaster Rock, N.B., on February 1, 1955. This is also the lowest temperature recorded anywhere in the Maritimes.

Perhaps the most significant feature of a New Brunswick winter is the marked variability in temperature from day to day. This is a product of the highly contrasting and fast-moving weather systems which traverse the province every two or three days.

The usual differences between coastal and inland localities are also seen in the length of the frost-free season. Along the Fundy shore 140 to 160 frost-free days occur on average, whereas in the central highlands of the Miramichi there are less than 90 days. A four-month frost-free season extends along the Gulf coast, and along the south shore of the Bay of Chaleur the growing season is extended by another week.

Precipitation: The Snowiest But Not the Wettest

Generally across the province, as the winter snowfall increases from place to place, the total precipitation for the year decreases. Cold winter temperatures and stormy northeasterlies combine to make New Brunswick the snowiest of the three Mar time provinces. Northwestern New Brunswick generally receives between 300 and 400 cm of snow annually, for about 33% of its annual total precipitation (rain and snow combined). On the other hand, the eastern and southern sections of the province receive 200 to 300 cm of snow, less than 20% of their annual total precipitation. Winter storms frequently bring rain to the Fundy coast and snow to the interior.

At Saint John the season's average snowfall of 293 cm occurs on 59 days between the middle of November and the middle of April. Although snowfalls are often deep, the snowcover comes and goes quickly. This pattern may repeat itself three or more times during the winter. In the northwest, however, the snowcover season lasts 160 days and is both reliable and persistent.

Spring and early summer are notably dry over New Brunswick, but there is ample water during the growing season. The interior highlands record about 1200 mm of rainfall a year, with the heaviest amounts falling during the summer months, a pattern characteristic of a continental-type climate. On the other hand, the southern shoreline receives a like amount, but with a slight maximum in fall and early winter. Elsewhere, 1000 mm is a representative yearly amount.

Stormy Weather

On average, thunderstorms occur between 10 to 20 days a year at any place in New Brunswick, and this is higher than over the remainder of Atlantic Canada. Normally only one thunderstorm a year is severe enough to produce hail. Tornadoes are rare but occur more often in New Brunswick, especially in the northwest, than in Nova Scotia. Even though tornado sightings are unusual, evidence of trees blown down by strong winds is not. When tornadoes do strike, they are usually rated as minor. This was not the case, however, on August 6, 1879, when a tornado ravaged the village of Buctouche, demolishing everything in its path. Seven people were killed, 10 were injured and 25 families were left homeless.

Freezing precipitation is a hazard on about a dozen or more days a year in New Brunswick. Hours of freezing rain or drizzle range from 34 hours a year at Fredericton to 59 hours at Moncton.

Storms associated with low pressure areas can occur at any time of the year but tend to be more severe and frequent in winter. These winter storms pack strong winds with snow often changing to rain and back again to snow. One of the most memorable storms of this kind in recent history struck eastern New Brunswick on January 4, 1986, walloping Moncton with 110 km/h winds and 67 cm of snow in 24 hours.

In the summer and fall, the main storm track passes through the Bay of Fundy and northeast through the Strait of Belle Isle. Weakened tropical storms and hurricanes affect the southern portion of the province with at least one heavy rainstorm every one or two years.

Winds blow predominantly from the west and northwest in the cold months and from the south and southwest in the warm months. Wind speeds average 15 to 20 km/h in winter and 12 to 15 km/h in summer. With some exceptions, winds tend to be lighter farther away from the sea coast. Along the coast, sea breezes are frequent, especially in the early afternoon on warm, sunny days under light regional winds. Local exposure is very significant. Open, treeless localities and the tops and slopes of ridges and hills are often very windy. Also, local topography causes funnelling of the wind in many circumstances. Windless conditions occur more frequently inland, anywhere between 5 to 12% of the time depending on local exposure. Coastal sites have fewer calms, with windless conditions occurring only 1 to 5% of the time. Strong winds above 50 km/h blow mainly from the west. Severe winds approaching hurricane force occur an hour or two each year along the coast, but are rarely measured at distances inland.

Sunny Maritimes

New Brunswick has some of the sunniest places in Atlantic Canada: Chatham is the only station in the region to record an average of 2000 hours a year. Perhaps the most surprising statistic is that Saint John in December reports nearly 100 hours of bright sunshine on average, more than any other station in eastern Canada! On the other hand, in July it reports one of the lowest sunshine totals in Canada. Across New Brunswick in an average year, sunless days number 75 and sunny days number between 140 and 160.

Fundy Fog

The well-mixed Atlantic waters off the Bay of Fundy are among the foggiest areas of the world, although not as notoriously foggy as the Grand Banks of Newfoundland. The season with the greatest contrast in temperature between sea surface and overriding air produces the greatest fog. At Saint John fog occurs on more than one quarter of the days of the year and 36% of the time in July. Sea fog is much more prevalent during the night and early morning than during the day. At Saint John early morning fog occurs on 60% of the fog days; by 2 p.m. the fog frequency drops to 18%.

Elsewhere across New Brunswick, the fall is the foggiest season, with occurrences on 4 or 5 days each month, but overall conditions are not unusually foggy. For example, in an average year, foggy days number 44 at Chatham, 24 at Campbellton, and 60 at Moncton; in comparison, Toronto has 35, London 50, Regina 29 and Vancouver 45.

River Flooding

The Saint John River has a history of flooding dating back to the arrival of the first European settlers. Within this century there have been at least six floods which have caused damage in excess of one million dollars. The worst flooding occurred in spring 1973 along the lower Saint John River in the Fredericton area, resulting in economic costs of $11.9 million ($ 40 million in 1990 dollars). A flood such as this is likely to occur only once in 70 years.

Conditions in late April 1973 were ripe for serious flooding. The winter snowpack was high, equivalent to 300 mm of water in some places. On April 27, two days after rivers crested at above normal levels, a storm moved into northern and central New Brunswick, bringing mild temperatures and a 75-mm rainfall. Rivers rose rapidly, in many cases to record levels, and peaked on April 29 and 30.

The total economic cost of the flood was almost $12 million. The most seriously affected area was the flood plain of the lower Saint John River in the Fredericton area and the farmlands downstream of Fredericton. Among the impacts on agriculture were a shortened growing season, physical damage to buildings and machinery, and reduced yields from crops and livestock. Even more serious was the loss of fertile soil.

At the peak of the flood, basements and ground floors of homes were flooded, trailers were water-logged, and cottages were ravaged by turbulent waters and floating debris. In Fredericton 260 homes and 193 businesses were damaged. The Lord Beaverbrook Hotel was closed for a few weeks as a result of the flooding.

Meteorological Moment

February 2 is usually the day when the groundhog checks his shadow, but for Saint Johners it has another significance. On that day in 1976 the city was racked by one of the fiercest storms ever to hit the Bay of Fundy in this century. At the height of the storm, winds were clocked at 188 km/h and waves reached heights of 12 m with swells as high as 10 m. Stronger winds have occurred, but they did not last as long as they did during the infamous Groundhog Day Storm.

Locals claimed that no storm since the legendary Saxby Gale of 1869 had caused such extensive damage. Tens of millions of dollars in losses were counted, including damaged docks and buildings, battered craft and mobile homes, and severed hydro poles and trees. Utilities were out and transportation slowed for a week. Everything in sight became coated with sea salt, when wind-driven spray was carried far inland. Strong winds blowing with the tide resulted in exceptionally high water levels that eroded huge chunks of coastline. An unusual phenomenon, never seen before, was the disappearance of many sea-birds, whlch never returned. Adding to the destruction were many broken water lines, frozen by bitterly cold Arctic air arriving on the heels of the windstorm.

Although the storm affected parts of central New Brunswick and all of Prince Edward Island, southern New Brunswick, especially Saint John, and western Nova Scotia were the hardest hit.

This information came from Environment Canada's The Climates of Canada