School buses across Lambton-Kent have been cancelled for Tuesday morning because of heavy fog conditions.
However, buses for the St. Clair Catholic and Lambton Kent District School Boards will run as normal Tuesday afternoon.
Langs Bus Lines for Aamjiwnnang First Nation are also cancelled for the morning only.
A fog advisory is in effect for most of southwestern Ontario.
Environment Canada said near zero visibility is expected over some areas but conditions are expected to improve later Tuesday morning.
Drivers are being reminded to turn on your lights, slow down and maintain a safe following distance.
