Prime Minister Justin Trudeau and Quebec Premier Philippe Couillard urged Canadians on Thursday to dig deep and contribute to the relief effort for flood victims in Ontario and Quebec.

The two leaders took to the skies over Gatineau to survey the devastation in western Quebec wrought by recent heavy rainfall and an overflowing Ottawa River.

Trudeau asked Canadians to be generous in helping their compatriots in need.

"It's extremely important for people watching on TV, people hearing about the challenges faced by so many communities, by so many families, to think about donating to the Red Cross," he said at a joint news conference with Couillard.

The prime minister said the relief effort is only just beginning.

"We know there's a lot of work still to do and all levels of government will continue to work together to take care of our citizens and to make sure we're doing the right things in the coming weeks (and) months of cleanup and hard work," he said.

There are roughly 2,200 military personnel on the ground helping to deal with the floods in Ontario and Quebec and Trudeau said they will be present for quite sometime.

"As the minister of defence has said, with the military, we arrive quickly but we leave slowly," he added.

Couillard acknowledged frustration in his province with the financial help that's been made available, saying Quebec is taking another look at the terms and the limits of its assistance program.

He said $800,000 has already been distributed, with more to come from the province and the Red Cross.

The federal government has contributed $1 million to the Red Cross and has assistance programs in place to assist flood victims.

Trudeau also said that as climate change continues to be a serious threat, Canadians need to be prepared to deal more often with severe weather disasters.

Meanwhile, the Quebec government again warned of heavy rain in at least one area of the province that is already struggling with high water levels.

The Mauricie region in central Quebec could receive up to 59 millimetres of rain by next Monday. Elsewhere in the province, water levels were continuing to drop.

More than 4,100 residences in Quebec have been affected by the floods and more than 3,000 people have had to leave their homes.

The floods have claimed at least one life in the province — a man whose car ended up in a surging river in the eastern Gaspe region. Authorities were searching again today for a two-year-old girl who disappeared in the same incident.

Besides the Canadian Forces personnel, a naval frigate was scheduled to arrive in Montreal on Thursday.

The vessel will serve as a command-and-control centre in the area, one official said, while crew members will provide assistance in Montreal and Trois-Rivieres.