Several sections of the Queen Elizabeth Way and Highway 407 were closed due to flooding around 7 p.m., wreaking havoc for motorists and cottage-goers heading home from Ontario's Civic Holiday long weekend.
OPP Sgt. Kerry Schmidt called the situation “absolutely dangerous.”
"I've been hearing reports of water, you know, up to the tops of vehicles, people are actually swimming from their cars," he told CBC News Monday night.
The catch basins were inundated with water and some of them were clogged, according to Schmidt.
Environment Canada issued a series of severe thunderstorm warnings and watches for much of southern Ontario Monday afternoon.
It has not been a great Civic Holiday weekend for commuters in the region.
The flood-related closures on the highways came less than an hour after the Burlington Skyway bridge reopened.
The Toronto-bound lanes of the bridge were closed for four days after a dump truck with its bucket raised slammed through the bridge on Thursday, severely damaging its structure.
In addition to highways, some residential streets in Burlington experienced flooding. There were also reports of basement flooding.