An intense trough of low pressure that pushed into the Maritimes has been bringing strong southerly winds and heavy rain to some places.
By the early morning hours on Friday, some areas had already picked up over 50 mm.
"And that rain will continue to linger," says Brian Dillon, a meteorologist at The Weather Network. "An additional 30-60 mm is expected through Saturday."
According to Environment Canada, the areas most at risk are southeastern New Brunswick, western and northern Nova Scotia and Prince Edward Island.
Parts of Newfoundland have seen a soaking as well.
"The good news is, summer-like temperatures are hanging on," says Dillon.
Nine new temperature records were broken in Newfoundland on Wednesday, including in St. John's where the daytime high reached 23.2 degrees.
"The normal temperature for this time of year is 16 degrees," adds Dillon.