Update: As of 5:00 am, the fog advisory has been lifted.
Environment Canada has issued a fog advisory for London-Middlesex, as well as Perth and Wellington counties.
The weather agency says fog has set in across parts of southern Ontario and it will become more dense Sunday evening, resulting in near zero visibility.
The fog is expected to lift Monday morning.
Drivers are being advised that visibility may be significantly and suddenly reduced to near zero. Travel is expected to be hazardous in some locations due to the fog.
