Environment Canada has issued a rainfall warning for B.C.’s South Coast, which could bring up to 80 millimetres of rain in just one day.

The weather agency issued the warning for Metro Vancouver, Howe Sound and the Sunshine Coast, with the wet conditions forecast to hit Friday.

Christy Climenhaga, a scientist with Environment and Climate Change Canada, said it will be a large amount of rainfall in a short period of time.

“What we have is an unseasonable moisture-laden frontal system that is moving in off the Pacific, bringing with it a lot of rainfall, which we don’t typically see in the summer months,” said Climenhaga. “We are going to be seeing a good dose of rain.”

A wet day on west Vancouver Island & the south coast tomorrow. Expecting 50 mm for Metro Vancouver, Squamish, Bowen Island & Gibsons with up to 80 mm over higher terrain before the rain ends Friday night. Take care near rivers and creeks for sudden rises in water levels #bcstorm pic.twitter.com/TG6NoCMHUx —@ECCCWeatherBC

Rain will be heaviest on Friday afternoon with 50 to 80 millimetres expected in most areas, and closer to 75 to 80 millimetres forecast at higher elevations, according to Climenhaga.

“It is going to be an incredibly wet one,” she said.

Environment Canada said the storm could cause flash flooding and water pooling on roads.

Bowen Island, Coquitlam, Gibsons, Maple Ridge, North Vancouver, Squamish and West Vancouver are all under the warning.

“If you are in that higher terrain, that’s where you are going to see those elevated amounts,” said Climenhaga.

People could see creeks, rivers and water levels rising quickly.

“Lower lying areas, if you’re camping, you could see some water pooling, so make sure you know your way in and out,” said Climenhaga.

The B.C. River Forecast Centre has also issued a high streamflow advisory for the South Coast, including Howe Sound, Sea to Sky, Pemberton and surrounding areas like the North Shore mountains.

The #BC River Forecast Centre has issued a High Streamflow Advisory for the South Coast including #HoweSound, #SeaToSky, #Pemberton & surrounding areas & North Shore Mountains. Stay clear of these fast-flowing rivers & potentially unstable riverbanks. More info:… pic.twitter.com/aT2aKJmGXZ —@EmergencyInfoBC

Be prepared if outdoors

Search and rescue members are asking the public to be prepared and plan ahead.

Christy Allan with Squamish Search and Rescue said the river levels are unpredictable and can rise quickly.

“Rain and low cloud can make it more difficult for search and rescue to access you,” said Allan. People are being advised to call for help early if they are in trouble.

“Be prepared for a potentially long response time,” said Allan.

SAR is asking people to consider delaying outdoor adventures until the forecast improves and the rainfall warning is lifted.

“It has been a while since we’ve seen a big dose of heavy rainfall in one day, so do keep an eye on your alerts if you are planning to head out of town or on the road,” said Climenhaga.

Environment Canada said it expects the rain to ease up late on Friday for the Sunshine Coast and after midnight for Metro Vancouver.