In Quebec, areas around Rigaud, Gatineau and certain regions of Montreal, states of emergency have been declared as hundreds have been evacuated.
A Concordia University professor and climatologist said the combination of the record rainfall, melting snow, and global warming is what led to the extreme flooding.
"When people go to their local centre they get information from the Red Cross".
Environment Canada said Montreal usually sees around 80 millimetres of precipitation in April, but this year, nearly double that amount fell on the city.
The flooding is not limited to Quebec, and unusually high rainfall has also caused flooding in the province of Ontario.
"I haven't seen anything like this since 1974", he said, adding that the area now is much more crowded and thus vulnerable.
"It's above flood stage in several areas from Fredericton down south", said Robert Duguay, a spokesperson with the province's emergency measures organization. Provincial authorities say water levels should peak across the province by midweek and begin receding.
New evacuations were carried out in Pierrefonds on the northwestern shore of the Island of Montreal as water levels rose rapidly following the breaching of three dykes.
"It's already the most serious in a few decades and it's going to get worse", he said.
At least 124 Quebec municipalities have been affected by flooding that has inundated 1,326 residences and forced the evacuation of 700 homes, according to Urgences Quebec.
"I strongly urge residents of le Mercier and other residents whose safety can not be ensured by emergency services to comply with the evacuation order", he said.
The situation in Ontario seems to be 'generally stabilizing, ' although there are many unstable local circumstances, he said. "But I know it's hard". He added that upward of 80 millimetres of rain fell between Friday and Sunday morning in the Trenton area.
The outer boroughs of Canada's second largest city have near waist-high water levels while many of Gatineau's residential streets look like canals.
He, like the premier, stressed patience in dealing with the situation, but said he was satisfied with the progress.
While the deluge has tapered off in the province, New Brunswick's St. John River is spilling its banks, prompting several road closures.
"Even shallow, fast-moving water across a road can sweep a vehicle or a person away".
A 76-year-old man was missing after a mudslide Saturday swept away his home in the community of Tappen, CBC reported.
Warmer temperatures has also caused snow to melt in British Columbia in Canada's west, combining with the rain to cause flooding and mudslides.