Scattered and isolated thunderstorms are forecast for Sunday evening in the Niagara Peninsula, eastern Ontario and southern Quebec.
And the storms are bringing all the usual suspects, including lightning, thunder, gusty winds and heavy downpours.
Thunderstorms are also possible for the Greater Toronto Area, capping off a muggy weekend from Ontario to Quebec.
It felt like 29 degrees in Toronto on Sunday afternoon as winds from the southwest drew up moist air. Stormy weather first rumbled through Sarnia and Windsor earlier in the weekend.
'Essentially what's triggering these thunderstorms is the pool of warm air that's coming in from the south. That moist air is creating the instability which is setting up the atmosphere to trigger these storms,' explains Weather Network Meteorologist Michelle Cassar.
Don't be so quick to put your umbrellas away for Monday, because conditions will still be unsettled in these regions.
In southern Ontario, spotty showers will dominate for the morning and afternoon hours, and by the evening, some areas could see some scattered rain.
For the latest on the thunderstorms in Ontario and Quebec, tune into The Weather Network on TV. Your Regional forecast comes up at the top and bottom of every hour.