I, like many Canadians, have a soft spot for autumn.
It may be the cooler fresh nights or sun-filled almost golden mild days. Maybe it’s the late season harvests or the changing colours of the maple, poplar and ash trees.
Whatever it is, September and October are months to be cherished. (Sorry November, you’re a much tougher sell.)
Canadians in the eastern half of the country have been especially spoiled in recent years, with summer warmth lasting into the month of October, in part thanks to very warm water off the east coast.
This helps build an upper level ridge and keep the mild air around longer into the fall.
This setup has returned again this year and will lead to a warmer than normal first half of autumn. The water is also abnormally warm off the west coast of Canada but in fall the results are different.
A trough is more likely to form near the coast and could lead to wet and cooler conditions just inland.
Now let’s get into the details…
The El Nino from last winter and spring is officially over. Forecasters predict a high likelihood of a neutral signal or perhaps a weak La Nina in the equator region of the Pacific this coming winter.
What is more remarkable is the very warm water off the west coast of North America.
WATCH: ‘The Blob’ blamed for weather extremes across Canada
If this ‘warm blob’ sticks around it will have serious consequences on the winter season across the country.
For autumn, the effects are smaller but could help keep it unsettled near the coast and cooler inland across the Rockies.
The forecast is for a typical fall but wetter and cooler for the southern part of the province.
A challenging forecast for the prairies, with cool and wet more likely west in Alberta and milder conditions more likely in Manitoba.
Above normal rainfall looks likely on the edge of warmer temperatures. I am concerned for a turn to much colder and snowy conditions in November and December which could set the stage for a rough winter ahead.
Ontario and Quebec
A semi-persistent ridge of high pressure resides over the southeast U.S. and extends into the Great Lakes at times.
This will continue to favour mild days and nights along with an abundance of sunshine from southern Ontario through most of Quebec.
The western and northern parts of Ontario will be closer to the battle ground between mild and cool, so above normal rainfall is expected.
I do expect a sharp cool down and perhaps an early appearance of winter for much of Ontario and Quebec but it won’t be enough to offset the first month of milder than normal temperatures.
The hurricane season remains very active with a number of named storms currently in the Atlantic and more on the way through at least early October.
It’s still too soon to say if the Maritimes will get hit again, even as the cleanup continues from hurricane Dorian.
I am concerned for another strike and water temperatures remain warm off the coast which would limit weakening as any storms approach. This mild water and Bermuda High will also lead to above normal temperatures through at least October.
Winter weather should get off to a late start for this region.
Yukon, N.W.T. and Nunavut
After a very mild summer overall, fall will also begin on a warm note compared to normal across the north.
I think this warmth will be too much to offset the cooler second half of autumn in Nunavut but near seasonal temperatures with several wild swings appear likely for the Northwest Territories and Yukon.
Watch for a building cold dome of air late in fall, setting the stage for what could be a chilly (and perhaps snowy) winter for much of Canada.