Toronto Pearson International Airport says it has temporarily grounded some flights due to dense fog in the area causing low visibility for pilots.
The airport says in a social media post that full operations are expected to resume throughout the day as conditions improve.
It says on foggy days like today, air traffic controllers regularly assess visibility and adjust hourly arrival rates to maintain safe operations.
Several domestic and international flights departing from Pearson and arriving at the airport were listed as delayed on the airport's website as of noon.
Evening flights are on schedule.
Environment Canada says in a fog advisory for the Mississauga area, where the airport is located, that near zero visibility may improve after rain passes through in the afternoon and evening, but could deteriorate again after the rain stops tonight.