Having an east coast mid-latitude location, the Maritime Provinces have a strongly continental climate with considerable variation in the seasonal temperature regime. Nearness to the ocean, however, modifies the continental influence and the Atlantic shores have lower summer temperatures and greater rainfall than inland areas.
At most stations January is the coldest month and July is the warmest, although in some parts of Nova Scotia February and August hold the honours, the reason being nearness to the ocean whose waters are slower to take on or give up heat than is dry land. Two important facts stand out. One is the great cooling effect of the elevation of the New Brunswick Highlands upon summer temperatures, the other is the moderating influence of the Atlantic Ocean upon its shores in the winter. Another function of temperature which is of importance, particularly to the farmer, is the occurrence of frosts. Notice how short it is in Northern New Brunswick. In fact, in the Central Highlands, frost may be expected in any month in the year. On the other hand, the Bay of Fundy, the Gulf of St. Lawrence and the Atlantic Ocean, by minimizing the difference between night and day temperatures, serve to prolong the frost-free season along their shores.
There is over twenty inches difference between the wettest and driest localities, the South Shore of Nova Scotia receiving more than 55 inches per year, while Northern New Brunswick receives only 35 inches or less. The effect of the oceanic influence is just the reverse, the South Shore of Nova Scotia gets only 70 inches or less while Northern New Brunswick gets more than 110 inches of snow. As a rule, ten inches of snow is counted as the equivalent of one inch of rain; therefore, in Northern New Brunswick over 30% of the precipitation falls as snow, whereas in Southern Nova Scotia only about 12% is snow, with a resulting very great difference in winter conditions. It is worth mentioning here, although no corresponding map is shown, that, in Northern New Brunswick, slightly more than half the yearly total falls in the warmer six months of the year, while, in Nova Scotia, the cooler half of the year is wetter. Worth noting too, is the number of rainy days per year, on the South Shore, it rains on two out of every five days, while, in the interior of New Brunswick, the proportion is one out of three. Moisture deficiencies may occur in the central and northern regions but seldom on the South Shore.
The Bay of Fundy and the South Shore are among the foggiest coasts on earth, while the Strait of Northumberland is relatively free from fogs. In the south and west most of the fogs occur in the summer, every other day in July usually being foggy. Toward the northeast, and especially in the Gulf of St. Lawrence, more fogs occur in the spring months.
From a study of these charts, the Maritime Provinces can be divided into eleven minor climatic regions. Two areas, the Central Highlands of New Brunswick and the Plateau of Northern Cape Breton, are elevated enough to warrant their separation as distinct climatic regions, although systematic data as to their characteristics are not available.
The peculiar location of the Maritime Provinces is the cause of considerable regional variation. The weather is controlled by cyclonic storms which in winter tend to pass along the southern border, inducing invasions of cold polar air, while in summer they pass to the north, drawing in warm air from the south and west. It is worth noting, too, that landward regions usually enjoy an earlier spring than marine locations, while the latter have a more prolonged and open autumn. In general, New Brunswick may be said to have a continental climate, while marine influence, in particular a much higher rainfall, characterizes Nova Scotia. Prince Edward Island, though surrounded by water, is more continental than marine.
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