The federal government is keeping a close watch on severe flooding in regions right across Canada as it deploys the military to battle "historic" water levels in Quebec.

Public Safety Minister Ralph Goodale's office said the formal request for help from the military came late afternoon, but details on where the troops will be sent, and in what capacity, are still being worked out.

"Things are evolving rapidly," Goodale's spokesman Scott Bardsley told CBC.

Today Prime Minister Justin Trudeau expressed support for the families and communities affected and praised the first responders and volunteers who are working to help in what he called an "extremely challenging situation." He pledged full support from the government.

"As a government we are in constant and regular contact with our counterparts in municipalities and provincial capitals in Quebec and Ontario," he said during an event in Montreal.

"We stand ready and willing to give whatever help the federal government can to help people through this situation and we will of course be there as the cleanup continues after the waters recede."

Late afternoon Friday, Quebec Public Security Minister Martin Coiteux asked for military assistance to help battle what he called "historic" flooding.

During a news conference in Montreal, Coiteux warned the situation will get worse in the next few days and would take several weeks to subside. But he said the government is mobilized and ready to handle the emergency as best as it can.

"Certainly this will test our resilience, but we're up to it," he said.

Goodale issued a statement Friday evening saying help was on the way and that the Government Operations Centre will monitor and assess the flooding situation as it continues to evolve.

"I have spoken with my provincial counterpart, Public Safety Minister Martin Coiteux, regarding the flooding situation," Goodale said in a statement. "On behalf of the government, the Minister of National Defence...Harjit Sajjan and I have accepted his formal request for federal assistance to help citizens in need."

Goodale advised people impacted by the flooding to follow the directions of local authorities and first responders.

Prime Minister Justin Trudeau pledges support to victims of floods in Quebec, Ontario. 0:36

The federal Government Operations Centre had beefed up its standby team as a precaution and is monitoring the flooding around the clock daily. The centre serves as the hub to co-ordinate the federal response to natural disasters and other emergencies.

Bardsley said assistance provided will depend on the requests, but noted that for the Fort McMurray fire, support included the Canadian Armed Forces, RCMP officers, geomatics, supplies from the Health Portfolio's National Emergency Stockpile System and coordination support from the Government of Canada Operations Centre.

Public Safety Canada also administers the Disaster Financial Assistance Arrangements program that helps provinces and territories cover the costs of response and recovery after large natural disasters "where these costs exceed what they might reasonably be expected to bear on their own."

Evacuation orders, flight delays

Heavy rainfall has affected communities in western Quebec and eastern and southern Ontario, causing home evacuation orders and the cancellation or delay of airline flights. The slow-moving system is heading to the Maritimes, with flooding in parts of New Brunswick and Nova Scotia possible this weekend.

Earlier today, National Defence said it was closely monitoring the situation and preparing to deploy where needed.

Public Safety Ralph Goodale says the government is ready to provide support to people affected by flooding 0:48

"Canadian Armed Forces personnel are in continuous liaison with Public Safety, and other federal partners," DND spokesman Evan Koronewski said in an email. "The CAF diligently plans for various contingencies to be ready to fulfil the direction of government, including the potential contribution to a federal response to an emergency in Canada."

NDP Leader Tom Mulcair said it should be "all hands on deck" as the flooding gets worse in coming days.

NDP Leader Tom Mulcair speaks to reporters during a visit to Yamachiche, Que. to observe the effects of severe flooding. (CBC)

"I don't think we should be waiting. At this stage in the game, it's so clear that we're heading for some record flooding .... we've got to start acting now," he said in a telephone interview with CBC News from Yamachiche, Que.

Mitigation funds

Mulcair urged the government to set aside significant funds for more extreme weather events such as forest fires and floods that are linked to climate change.

"We've got to be adding more money to the pot, not less, because this type of flooding, this type of event that's directly related to what we're going to be seeing with global warming, we've got to be getting ready for it," he said.

Gatineau MP Steven MacKinnon says this looks like “a once in 20 years event”, discusses what is being done to help flood-affected residents in his region 4:36

Environment Minister Catherine McKenna said while you can't link any single weather event to climate change, there is no doubt the impacts are longer-term, That is why the government is investing in "adaptation," from addressing buckling roads in the melting Arctic to researching resilient crops.

"This is something that is real. We are seeing the impacts of climate change, and that's why we're taking it seriously," she said, adding the government is tackling climate change while creating green jobs for innovation and infrastructure.

Goodale's office said this year's budget included $2 billion for a Disaster Mitigation and Adaptation Fund to support national, provincial and municipal infrastructure required to deal with the effects of climate change.