Multi-day storm risk in southern Ontario stays put, but pattern change looms
Dew points have been pushed into the low 20s, giving the classic, muggy humidex in the mid-30s across southern Ontario, leading to another thunderstorm risk on Thursday
Heat and humidity are building across Ontario this week, accompanied by an increasing risk of thunderstorms.
Temperatures will feel like the 30s, with humidex values in the mid-30s. The warmest days are forecast for Thursday.
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The muggy air will help to fuel a thunderstorm risk, as well with the threat for torrential downpours at times.
Another threat of thunderstorms on Thursday with muggy air mass
Overnight Wednesday into Thursday morning, thunderstorms are forecast to track into the region from Michigan, bringing rounds of thunder, lightning, and heavy rain across southern Ontario, including the GTA.
Another very mild night, too, with lows hovering near 20°C for a couple of communities through the pre-dawn hours on Thursday. Lows will be as warm as 23°C in Windsor. The average low this time of year is 13°C for Toronto and 15°C for Windsor.
Spotty showers and storms may slow the early-morning commute, so plan ahead and leave earlier if need be.
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By Thursday afternoon, isolated thunderstorms may develop along a trailing trough and instability, potentially affecting the GTA and areas farther east. The biggest risk is in eastern Ontario, but storms still forecast to be scattered.
Thunderstorm activity is also being monitored for Thursday overnight, with storm complexes potentially moving in from the U.S. Great Lakes region. However, there is still considerable uncertainty regarding the severity and timing of these storms over southern Ontario.
The higher risk would be extreme southwestern Ontario through the pre-dawn hours on Friday.
Southern Ontario to be well-watered over the next two weeks, noticeable drop in temperatures
After some above-seasonal temperatures, a deep trough will spin across Ontario by next Sunday--pushing temperatures to well below seasonal, especially for northern areas.
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Looking ahead, most of next week will be cooler than seasonal with a few rounds of showers and thunderstorms, but temperatures should trend back to near seasonal, and possibly above seasonal, for a couple days next weekend.
No consistent heat is in sight (after this week), and the pattern should continue to be unsettled at times into the final week of June.