Summer of 2012 will feature above-normal warmth for much of Canada, while more thunderstorms than usual target eastern Ontario and southern Quebec. Nova Scotia and Newfoundland will be more susceptible than normal to tropical system impact later in the summer.
There will be widespread above-normal warmth across much of the nation, especially across the southern Prairies. Extended spells of heat are anticipated to grip the southern Prairies.
It will be hot for Calgary and Edmonton with below-normal rainfall.
A dome of high pressure will be set up across the central Plains of the U.S. early in the season. It will build northward and westward across the Rockies as the summer progresses, promoting the hot and dry weather across the Prairies.
An exception to the widespread warmth will be an area from Windsor, Ontario, to Montreal, Quebec. In this zone, any prolonged heat spells will be few and far between. Instead, near-normal temperatures are expected.
Active, stormy weather will occur across eastern Ontario and southern Quebec, keeping long heat spells at bay. Cities that lie in the path of more stormy weather this summer include Ottawa, Ontario, and Montreal and Quebec City, Quebec.
"There will be cooler air aloft this summer, making the atmosphere more unstable and conducive for thunderstorm development," said Expert Senior Meteorologist Brett Anderson.
Meanwhile, there is an increased tropical storm threat for Nova Scotia and Newfoundland later this summer, since steering currents in the tropics may be directed toward Atlantic Canada.
When making a long-range forecast, meteorologists look back at analogue years where there was a similar pattern to help make the forecast. Anderson explained that the summer of 2006 was one of the analogue years analyzed for looking at potential tropical impact.
In 2006, a total of four weakening tropical systems had some impact on Atlantic Canada. There was a transitioning pattern toward an El Niño during the summer of 2006 similar to how AccuWeather.com Long-Range Forecasters expect the pattern to be in transition this summer.
"A lot of years that are transitioning into El Niño have seen tropical systems approach Nova Scotia and Newfoundland," Anderson added.
It will also be a warmer and more humid summer than usual with above-normal rainfall for eastern parts of Atlantic Canada.
St. John's, Newfoundland, is among the cities forecast to have above-normal rainfall for the summer. There will be more cloudy and foggy days compared to normal.
Meanwhile, in western Canada, it will be a pleasant summer for outdoor activities in British Columbia, including in the Canadian Rockies.
Temperatures and precipitation will be near-normal for Vancouver.
The late-season swelter will continue along much of the Atlantic Seaboard through the week as tens of millions head back to school and work.
The next Atlantic tropical depression or storm may take shape in the southwestern Gulf of Mexico's Bay of Campeche during the next couple of days.
A second volcanic eruption occurred on Sunday morning in Iceland in the same area that had one on Friday.
Severe thunderstorms will threaten holiday festivities across parts of the Midwest to close out the extended Labor Day weekend.
While flooding is a threat, monsoonal rains will be beneficial for most areas across northwest India this week.
Gusty winds, large hail and power outages occurred Sunday into Monday morning in the north-central United States.
Los Angeles, CA (1955)
110 degrees, hottest day ever in September. This mark was tied September 4, 1988.
Milwaukee, WI (1988)
Hottest summer on record. Six days of 100 degrees or greater and 36 days of 90 or above. Average temperature of 73.8 beat the old record of 72.8 set in 1921 and 1955. The normal average tempera- ture for a summer in Milwaukee is 68.3 degrees.
Washington Co., IA (1897)
Hail fell and drifted in piles 6 feet deep in Washington County.