Heavy storms usher in the first day of summer in Southern Ontario

The first official day of summer began in style across Southern Ontario as several severe thunderstorms swept across the region on Thursday.

The continued heat and humidity will bring more thunderstorms Friday and Saturday into the beginning of the weekend. Watch for lightning, heavy rain and gusty winds in the more severe cells that rise.

MUST SEE: Storms threaten Ontario's first weekend of summer, a look at early July

Severe storms possible on Friday

Southern Ontario will continue to experience muggy and unsettled weather through Friday. Even though the worst of the heat subsides, we will still see enough instability with daytime heat and lingering moisture to trigger another round of widespread thunderstorms across the region. However, because the storms will be scattered, not everyone will get one.

RELATED TOPICS: Attention? Warning? How we communicate severe weather in Canada

Given the current dynamics, we could see some thunderstorms that meet severe criteria across southwestern Ontario and the Greater Toronto Area. The strongest storms could bring torrential rain and locally gusty winds.

Some storms may dump 50 mm of rain in just a few hours. This could lead to localized ponding on roads beneath slower moving cells. Flash flooding is possible in urban areas.

Danger of storms again on Saturday

We are monitoring the development of a low pressure system moving towards Ontario early this weekend.

This system, moving into the Great Lakes region, will bring a warm front across eastern and central Ontario on Saturday morning and southern Ontario in the afternoon. This will bring widespread, significant rainfall to the province and pave the way for thunderstorms to move in from Lake Huron.

As they arrive, thunderstorms are likely to form along the warm front, bringing the threat of heavy rain and strong wind gusts to communities in the path of these storms.

There is still some uncertainty about exactly where the storms will develop and where they will move, but major cities such as London, Hamilton and the Greater Toronto Area are at risk of severe storms on Saturday.

Further north in Central Ontario, widespread rain is expected, with the heaviest rainfall expected between Sault Ste. Marie and Eastern Ontario, where 50-75+ mm of rain is expected.

The widespread rain will also reach Quebec and spoil the Saint-Jean-Baptiste Day celebrations.

WATCH: Storms and landslides rage across Southern Ontario Thursday

Click here to watch the video

Stay tuned to the Weather Network for the latest forecasts across Ontario.