Environment Canada has issued a dense fog warning southern Ontario alert for several communities across Durham Region and other parts of the province early Sunday morning.
The warning covers areas including Oshawa, Pickering, Southern Durham Region, Markham, Vaughan, Richmond Hill, Lindsay, Belleville, Quinte West, and parts of eastern Ontario.
According to Environment Canada, the dense fog warning southern Ontario advisory was issued after thick fog developed overnight, significantly reducing visibility in some areas to near zero.
Officials say driving conditions may remain dangerous through the early morning hours until the fog gradually lifts later in the day.
Motorists travelling throughout Durham Region are being urged to use caution, especially on highways, rural roads, and low-lying areas where visibility conditions can change rapidly.
Environment Canada advises drivers affected by the dense fog warning southern Ontario system to reduce speed, use low-beam headlights, and maintain extra distance between vehicles.
The weather agency warned that visibility may become “suddenly reduced at times,” increasing the risk of collisions and hazardous travel conditions during the morning commute.
Communities throughout Durham Region, including Oshawa and Pickering, are expected to experience periods of dense fog before conditions improve later Sunday morning.
The dense fog warning southern Ontario bulletin was last updated by Environment Canada at 3:52 a.m. EDT on Sunday, May 17, 2026.
Fog advisories are common during spring weather transitions when overnight cooling and increased moisture create conditions favourable for reduced visibility.
Weather officials recommend postponing non-essential travel until conditions improve if visibility becomes severely limited.
Drivers are also encouraged to remain alert for changing road conditions and avoid using high-beam headlights, which can reflect off fog and worsen visibility.
As weather conditions continue changing throughout southern Ontario, residents are advised to monitor Environment Canada updates for additional advisories or travel warnings connected to the dense fog warning southern Ontario system.
