Weather pattern flips hit Canada's summer for July and August

Yahoo

19-06-2025

Summer weather has been sporadic so far across Canada. Parts of the country have already experienced record heat, drought, devastating wildfires and widespread smoke. Meanwhile, other areas are still waiting for consistent warm weather.
However, mid-June has featured a dramatic pattern reversal. Much cooler spring-like conditions have returned to areas that have already endured record breaking heat. Meanwhile the areas that have been waiting for warmth are seeing a sudden flip to mid-summer-like heat.
Will summer continue to play hide and seek, with dramatic but temporary appearances or will we finally settle into a more consistent pattern?
Please read on for an update on what we expect during the months of July and August across Canada.
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The official first day of summer is Friday June 20th. However, the first week of summer will be a tale of two seasons across Canada. The graphic below shows the temperature anomalies that we expect for the first official week of summer.
The various shades of blue highlight cooler than normal temperatures, which will be widespread from southern B.C. to Labrador. This region will feel more like spring for several days with single-digit high temperatures for parts of the Prairies this weekend and substantial snow for alpine regions in the Rockies.
However, across northwestern Canada and from the Great Lakes to the Maritimes, hot weather will dominate during the first week of summer. This will include a couple of days of record-breaking heat and humidity across southern and northeastern Ontario and southern Quebec.
However, this pattern will be temporary. During the final days of June and the first week of July, we expect that the focus of heat will slowly shift back to western Canada, while Ontario, Quebec, and Atlantic Canada will trend cooler—closer to seasonal.
While the weather will still be changeable at times, we expect that this will become the dominant pattern for most of July and August and even into the first half of September.
So, despite the chilly start to the season, we still expect a very hot summer across the Prairies and the interior of B.C.
From Ontario to Atlantic Canada, temperatures will be more changeable, with some hot days, but there will be periods of cooler weather as well. We certainly can't rule out another heat wave later in the summer, but we do not expect consistent heat during July.
Daytime temperatures are expected to balance out to near normal, but warmer nights (due to higher than normal humidity) will cause parts of the region to tip warmer than normal overall.
The more changeable conditions across eastern Canada will also be associated with a more frequent threat of showers and thunderstorms, which should result in near-normal or above-normal precipitation totals for most of the region.
While western Canada is seeing much-needed (and even excessive) rain during June, we expect that a much drier pattern will return for July and August.
Keep in mind that below-normal precipitation does not mean that there won't be any rain or storms. Thunderstorms with localized torrential rain will still occur, but the storms will be less frequent and less widespread than what we typically see during summer.
Unfortunately, below-normal rain totals in combination with warmer-than-normal temperatures can have a negative impact on agriculture and result in an increasing wildfire danger. And, as we have already seen this year, smoke from wildfires can spread across most of Canada and impact places that are experiencing a much cooler and wetter summer.
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