Two large towns which are important centres for cottage country — Bracebridge and Huntsville — have declared emergencies after heavy rains and melting snow washed out roads, damaged homes and flooded businesses.
"Expect the worst. This is going to be a bad one, a really bad one. This is going to be worse than 1985 which was probably the biggest we've seen," said Huntsville Mayor Claude Doughty.
The district received 50 millimetres of rain over Thursday night and Friday morning.
Doughty said about 500 homes — and an estimated 1,000 residents — have been affected by the floods.
"At this point there are properties that are being affected and threatened, but primarily the biggest thing we're struggling with right now are the road networks being flooded out," Doughty told CBC News on Saturday morning.
"That means we've got people sealed in in certain areas, or sealed out of the area they need to get in to where their home is."
With more rain expected, police and city officials are advising anyone living in low-lying areas to leave.
Power has been shut off in some areas as a safety precaution.
Wendy Dingman and her family have been forced to leave their Huntsville home because of the rising waters.
"The Salvation Army is covering three days for us at the Comfort Inn," said Dingman. "So we are prepared to stay there for some time."
In total about 100 Huntsville residents are out of their homes.
Melissa Stewart came from Toronto to visit her parents. Instead she's helping to pump out the basement.
"I was shocked. My mom said it was bad but I didn't think it was this bad," Stewart told CBC News.
The Stewart's home backs on to the Big East River. All of the residents on the west side of river have been told to leave their homes.
The town of Huntsville estimates at least $1 million in damage to infrastructure, so far.
Bracebridge has declared a similar state of emergency with the Muskoka River that runs through the centre of town overflowing its banks.
The town has opened the Bracebridge Sportsplex for use as a temporary shelter.
"The Sportsplex will be open 24 hours per day until further notice. Anyone displaced because of the flooding and requiring temporary shelter can go to the Sportsplex as necessary," said the town in a statement on its website.
Ontario Provincial Police have set up a command post and say dozens of roads have been closed in the Huntsville and Bracebridge areas.
The OPP say they expect more road closures and more evacuations over the weekend.