The heat warning has been dropped and temperatures will range in the mid-20's to start the week.
But there is a special weather statement covering Huron, Perth and Wellington counties and most of southern Ontario. Environment Canada says a slow-moving low pressure system over eastern Texas is forecast to drift north reaching the lower Great Lakes tomorrow.
Rain, between 25 to 40 mm, is expected.
As of 6:10am, Grey and Bruce counties are now also covered under the special weather advisory.