Nearly half a million lose power after torrential rains pound southern ...

Nearly half a million Hydro-Québec customers are without power Friday evening after torrential rains drenched the southern portion of the province throughout the day, causing localized flooding in several areas.

At least one Quebec municipality has declared a state of emergency. La Macaza, about 170 kilometres northwest of Montreal in the Laurentians region, has opened a shelter for victims and an emergency co-ordination centre. Two roads are closed there, Lac-Chaud and Lac-Macaza.

Mayor Yves Bélanger said one person has been forced to flee, others are unable to leave and emergency services are checking on residents of isolated properties.

Urgence Québec said on the social media platform X that several residents in the province have been trapped by floodwaters. It encourages people to check their municipality's social media pages and websites for crucial information about disaster relief.

A total of 70 to 100 millimetres of rain was forecasted for the island of Montreal area Friday. The city's rainfall average for the whole month of August stands at 94.1 millimetres.

Some areas, such as Berthierville—Saint-Gabriel in the Lanaudière region, are expected to get up to 120 millimetres of rainfall by Saturday. In the municipality of Saint-Zénon, a landslide caused the closure of Route 131 early Friday evening.

Peter Kimbell, a warning preparedness meteorologist with Environment and Climate Change Canada (ECC), said 80 millimetres fell in Montreal by 3 p.m. In Granby, Que., about 80 kilometres east of Montreal, 103 millimetres of rainfall was recorded.

The amount could be more in other areas, he said, and the rain isn't letting up just yet.

"Another 50 or more millimetres for the Montreal area still to come late this afternoon, this evening," he said. "So it's going to get worse before it's all over."

Several flights at Montreal's international airport were either delayed or cancelled Friday evening.

This comes after overnight rains already left some Montrealers with wet basements. Among them was Michael Simeonidis who was woken up at 5:30 a.m. by his water alarm.

His basement on Norman Street in the borough of Saint-Laurent flooded for the second time in a month.

"It's not so bad," he said standing in about 30 centimetres of water. "I mean it's bad, but it's not so bad because there's no furniture. Everything was destroyed the first time — July 10."

That's when the sewer at the end of his street was overwhelmed as remnants of Hurricane Beryl passed through. On Friday morning, it struggled to cope with the remnants of tropical storm Debby.

Saint-Laurent Mayor Alan DeSousa said Montreal needs to look into why the area is so susceptible to flooding.  

Montreal roadways flood

Transport Ministry spokesperson Louis-André Bertrand said in Montreal, Highway 40, near Côte-de-Liesse Road, and Highway 13 northbound were affected.

"This is an extraordinary amount of rain," said Bertrand. "No sewer system can take that."

Bertrand said the agency focused on clearing roads of debris in the lead-up to the storm to facilitate drainage.

WATCH | Flooding in Montreal after heavy rain: 

The remnants of Hurricane Debby hit Quebec on Friday, bringing torrential rains that flooded roads in Montreal.

The downtown Montreal shelter Resilience is also experiencing flooding, according to a post on X by Na'kuset of the Native Women's Shelter of Montreal. 

Montreal spokesperson Hugo Bourgoin said the city's 311 service centre received more than 250 calls about flooding as some underpasses and residential basements have been affected. He said teams have been in the field, working on solutions.

He said people are encouraged to call 311 if street catch basins are overflowing or water is exceeding curbs and advancing toward private property.

"Due to climate change, projections indicate that very intense rains will occur more frequently," he said, adding that Montreal is taking steps to enhance its resilience against such environmental challenges.

Building owners are encouraged to consult Montreal's website for tips and recommendations on how to properly protect their properties against sewer backups and urban flooding.

Event cancellations in Quebec City and Montreal

The rainy and windy forecast has led to event cancellations in Quebec City.

Comedy festival ComediHa! Fest is cancelling its outdoor shows hosted by Phil Roy scheduled for later Friday evening. 

Music festival Cigale also announced the cancellation of artist Loud's show, which was scheduled for 7 p.m. at Quebec City's Old Port.

Strong winds and heavy showers threaten the safety of its stage crew, the festival said in a Facebook post Thursday.

Pride Montreal has also decided to cancel all of its outdoor events Friday, which included its Community Day on Ste-Catherine Street East and drag evening at the Olympic Stadium. The festival's indoor events will go on as scheduled.