TORONTO, April 17, 2026 — In case you have not looked out the window or ventured outside. Much of the GTA is experiencing low visibility due to fog this evening as Environment and Climate Change Canada has issued two yellow alerts: one for fog on Friday, and the other for impending rainfall coming on Saturday, which could cause flooding.
Near-zero visibility in fog is expected over some areas in the GTA on Friday due to dense fog, and this will be followed by 10 – 20 mm of rainfall starting early Saturday and continuing into the afternoon. Now, because the ground across the city is already saturated from the rainfall this past week, there is a likelihood of flooding in some areas.
The dense fog that developed near Lake Ontario on Friday is caused by warm, moist air passing over the lake’s cold water. This is a common occurrence here in the spring due to the proximity of Lake Ontario and other large bodies of water. This phenomenon, known as advection fog, will be present throughout Friday and will continue to spread inland this evening.
The fog could potentially linger through the night and into Saturday morning as the rain hits.
Getting around will likely be hazardous in some locations. Visibility will likely be suddenly reduced at times.
Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to ONstorm@ec.gc.ca or post reports on X using #ONStorm.