Ontario's last hurrah for summer-like heat and thunderstorm risk this year?

After the remnants of Hurricane Isaias depart southern Ontario on Sunday, perhaps the final surge of summer-like warmth this year will make a brief appearance this week.

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The week will start with unseasonably warm, July-like conditions, possibily the final time this year for southern Ontario. But the pattern brings the energy for thunderstorms Monday night and Tuesday.

Following the storms, an upper-level low will drag in much colder air, leading to a significant temperature drop in time for next weekend.

Temperatures to soar early this week, with thunderstorm risk

For those heading out early on Thanksgiving Monday, expect reduced visibility on the roads with patchy fog, thanks to residual, departing moisture from former Hurricane Isaias.

Through the day, the fog burns off, allowing for a mix of sun and cloud to enjoy. Mild temperatures of around 20°C can be expected--at least five degrees above seasonal.

However, conditions will change Monday overnight into early Tuesday, when a fairly potent low will spreads showers and thunderstorms across southern Ontario.

But it gets even warmer on Tuesday as temperatures climb into the mid-20s. Windsor is forecast to hit 28°C--remarkable heat for this time of the year.

As the low-pressure system continues across southern Ontario, showers and thunderstorms will track across the region.

By the end of the week, as we approach next weekend, temperatures will be drastically cooler. Some areas will only hit the single digits for highs.

DON'T MISS: Canada's Winter Sneak Peek: El Niño puts record warmth in play

However, temperatures are expected to be changeable through the following week. Above-seasonal temperatures are then expected to return for late October and November.

Stay tuned to The Weather Network for the latest forecast updates for Ontario.