Final rain, storm threat after days of torrential downpours hit parts of Ontario
Thursday will bring the last round of afternoon storms and localized downpours in Ontario, with activity focused on eastern parts of the province
Southern Ontario is set for another round of heavy rain through Thursday, following localized flooding that affected parts of the Greater Toronto Area (GTA) on Tuesday evening and Wednesday.
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Early Wednesday, a series of intense, moisture-laden thunderstorms moved along the northwestern shoreline of Lake Erie, bringing prolonged heavy rainfall and significantly increasing precipitation amounts.
By midday Wednesday, radar estimates showed rainfall totals ranging from 100-200 mm in a localized area of extreme southwestern Ontario.
Thursday marks the last day of afternoon storms and localized downpours in Ontario, with activity limited to eastern parts of the province.
Localized downpours on Thursday, heaviest totals likely across eastern Ontario
The last two days have highlighted the challenges of forecasting rainfall totals in these scenarios, with differences of up to 100 mm observed over just 10 km in many areas.
While the GTA and southwestern Ontario could still see afternoon and evening downpours on Thursday, the faster-moving rain pockets are expected to reduce the risk of flooding.
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Scattered showers and thunderstorms are expected in eastern Ontario through the day as the system continues to track eastward.
It is important to remain weather-aware, and stay up-to-date on all of the latest watches and warnings.
High pressure is set to move in behind this system, establishing another stretch of dry weather heading into the weekend.
Wettest stretch of weather since last September
Toronto Pearson Airport (YYZ) recorded 38.1 mm of rainfall on Tuesday as slow-moving thunderstorms rolled through the region. This marked the city’s wettest day in over two months, since July 20, which saw 48.1 mm.
Dry conditions have dominated the region, with much of southern Ontario receiving less than half the normal rainfall from late August through most of September, leading to widespread drought concerns.
The 82 mm of rainfall recorded at Pearson Airport over the past four days (Sept. 21–24) marks the wettest four-day stretch since the same period last year, Sept. 21–24.
A pleasant first weekend of fall
Friday will bring partly to mostly sunny skies, with highs reaching the lower 20s. On Saturday, expect partly sunny conditions with a slight chance of an isolated shower. Temperatures will range from the low to mid-20s but will stay cooler near the west end of Lake Ontario, where an east breeze and lingering morning clouds could limit daytime heating to the lower 20s.
Sunday looks mostly sunny and warm, with highs in the mid-20s and the potential to reach the upper 20s, providing a summertime feel for the final Sunday of September.
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Monday is forecast to be sunny and warm, as well. By midweek, temperatures are expected to dip closer to seasonal norms, with highs in the upper teens.
Warmer-than-normal conditions are likely to return late in the week and continue through the weekend.
Stay with The Weather Network for all the latest on conditions across Ontario.