Geography of Newfoundland and Labrador - Climate

Climate

The province has been divided into six climate types, but in broader terms Newfoundland is considered to be a cool summer subtype of a humid continental climate, which is greatly influenced by the sea since no part of the island is more than 100 kilometers (62 mi) from the ocean. Northern Labrador is classified as a polar tundra climate, southern Labrador is considered to have a subarctic climate.

Monthly average temperatures, rainfall and snowfall for four communities are shown in the attached graphs. St. John's represents the east coast, Gander the interior of the island, Corner Brook the west coast of the island and Wabush the interior of Labrador. The detailed information and information for 73 communities in the province is available from a government website. The data used in making the graphs is the average taken over thirty years. Error bars on the temperature graph indicate the range of daytime highs and night time lows. Snowfall is the total amount which fell during the month, not the amount accumulated on the ground. This distinction is particularly important for St. John's where a heavy snowfall can be followed by rain so that no snow remains on the ground.

Surface water temperatures on the Atlantic side reaches a summer average of 12 °C (54 °F) inshore and 9 °C (48 °F) offshore to winter lows of −1 °C (30 °F) inshore and 2 °C (36 °F) offshore. Sea temperatures on the west coast are warmer than Atlantic side by 1 to 3 °C (approximately 2 to 5 °F). The sea keeps winter temperatures slightly higher and summer temperatures a little lower on the coast than at places inland. The maritime climate produces more variable weather, ample precipitation in a variety of forms, greater humidity, lower visibility, more clouds, less sunshine, and higher winds than a continental climate. Some of these effects can be seen in the graphs. Labrador's climate differs from that of the island not only because it is further north, but also because the interior does not see the moderating effects of the ocean.

Weather systems affecting Newfoundland usually originate from the west, over mainland Canada, or from the southwest, from the east coast of the United States. Cyclonic storms consist of an area of low atmospheric pressure characterized by inward spiraling winds that rotate counter clockwise in the northern hemisphere. Such storms passing to the south of the island bring strong northeasterly winds sweeping in off the open North Atlantic Ocean. These storms are sometimes referred to as Nor'easters and are responsible for the worst of Newfoundland's weather. High winds sweeping over a large surface of ocean can build up very large waves. The frequency and severity of storms is greatest between November and March, although they may occur at any time of the year.

One of these storms was the "Independence Hurricane", which struck eastern Newfoundland on September 9, 1775. About 4000 sailors, mostly from the British Isles, were reported to have been drowned.

During a violent storm on February 15, 1982, the drilling rig Ocean Ranger capsized and sank on the Grand Banks, 300 kilometers (190 mi) east of St. John's. The entire 84-man crew perished, making it the worst Canadian marine disaster in decades.

Newfoundland and Labrador has the strongest winds of any of the provinces, with most places having average annual wind speeds over 20 kilometers per hour (12 mph).

Freezing rain is common in Newfoundland where it is known as "silver thaw". Freezing drizzle or freezing rain occurs on average of 150 hours each winter, most commonly in March. One such storm struck St. John's on April 11, 1984 and lasted three days. Ice almost 15 centimeters (5.9 in) thick disrupted electrical power to 200,000 people on the Avalon Peninsula for days.

Newfoundland receives less than 1600 hours of sunshine per year, much lower than the Canadian average of 1925 hours. Summer months average 187 hours of sun while the December average is 60 hours.

Newfoundland is also known for its fog which occurs most often in the spring and early summer because of the contrast between sea and air temperatures. Argentia has 206 days of fog per year. Fog in Newfoundland is frequently accompanied by strong onshore winds; while usually winds disperse fog, here the fog is too widespread for this to occur.