Burlington is cleaning up after two months' worth of rain fell Monday night as thunderstorms swept through much of southern Ontario.

And after highways were flooded and motorists were left stranded, police described the situation as "absolutely dangerous."

'I have great empathy for people who have been flooded more than once,' says Mayor Rick Goldring, who held a media conference with Scott Stuart, Burlington's general manager of development and infrastructure. (Samantha Craggs/CBC)

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 on Monday night.

The catch basins were inundated with water and some of them were clogged, Schmidt said.

At the height of the storm, much of Burlington — from Appleby Line to Brant Street, both north and south of the Qeen Elizabeth Way — was under water, Halton police said.

"What happened was a number of the creeks and small little rivers throughout the city just got inundated with the amount of water we received, and so unfortunately they had nowhere to go and a number of them crested at the same time," said Staff Sgt. Stephanie Jamieson.

Long weekend traffic chaos

Rob Born, who was trapped in his car until a tow truck came to haul him out, kept his sense of humour and said the flood saved him a shower.

"The water came in up to the bottom of the steering wheel, so I'm pretty much soaked right now." he told CBC News Monday night. "Never had that happen before. You see it on TV all the time."

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. Halton Region fielded about 2,200 calls, and city officials estimate that more than 500 basements were flooded.

Mayor Rick Goldring's home was among those flooded. "I’ve lived in my home for 20 years," he said. "This is the first time I’ve had water in the basement."

The city is assessing the damage, he said, and will take a closer look in the fall at whether it needs to improve its infrastructure to prevent this from happening again. Its immediate priority is to ensure that all roads are passable.

"There's obviously a concern about contamination in the water and a concern about some elderly residents who've been affected this year," Goldring said.