The areas of Barrie and Collingwood have received a tornado warning.
Just after 3 p.m., Environment Canada issued the alert.
A severe thunderstorm warning has also been issued for other adjacent municipalities, including Midland and Orillia.
According to the forecast, some locations may experience heavy rain with accumulations of up to 50 millimeters.
“Environment Canada meteorologists are tracking a severe thunderstorm capable of producing very strong wind gusts, up to nickel size hail and torrential rain,” that warning states.
Environment Canada says that a severe thunderstorm capable of producing a tornado is currently located near Duntroon and moving east at 60 km/h.