Conditions favourable for severe thunderstorms will build across portions of Ontario on Saturday as a low-pressure system from northern Ontario sweeps over the Great Lakes region. Heat warnings are in place for much of southern Ontario as the hot and humid weather settles in this weekend.

A risk for thunderstorms will redevelop on Sunday as a cold front pushes into an unstable atmosphere across southern Ontario. The storms will develop inland and track through the Greater Toronto Area and into eastern Ontario. Some of Sunday’s storms could turn severe.