VANCOUVER -- An expected heat wave is threatening to incinerate temperature records across southern British Columbia this weekend, forcing officials to urge caution while in the forests, implement campfire bans, and turn on additional drinking-water fountains.

Environment Canada issued a special-weather statement on Thursday for Metro Vancouver. It forecasts a strong ridge of high pressure will build over Western Canada on Friday, allowing hot air to invade southern sections of the province.

The mercury is expected to hit the low 40s in the southern Interior and the low 30s on the south coast, and the agency predicts several temperature records will be shattered.

Lisa Coldwells, an Environment Canada meteorologist, said temperatures in the southern Interior are expected to be 15 C above normal.

"Normally, in the end of June, you're looking at a daytime temperature of about 26 C, and for this weekend it's going to be 40 C," she said. "We're looking at Saturday and Sunday, temperatures rocketing up to 40 C, and that of course will be breaking daily records."

She said June 29, 2008, was the last day it got as hot, and that's when the thermometer hit 39.1 C.

Due to the dry forests and rising temperatures, the Wildfire Management Branch announced it will implement a campfire ban across the Coastal Fire Centre on Saturday at noon, excluding northern Vancouver Island, the mainland's mid-coast and Haida Gwaii.

Five other fire centres have not yet implemented campfire bans. Kelsey Winter, a fire information officer, said human-caused fires have not yet been a huge concern in the Kamloops Fire Centre.

"When we look at the campfire ban, we consider the weather, we consider fire activity, as well as the amount of non-compliance that we've been seeing with the campfires, and right now there aren't enough zones in the Kamloops Fire Centre that have reached that critical threshold with fire activity and weather that would deem the campfire (ban) necessary," said Winter.

She said a campfire ban was implemented last year on July 15.

To beat the heat and keep people hydrated, the City of Vancouver has identified the locations of 250 permanent and six temporary water fountains.

It has also issued a "plea for the trees," asking residents to help water 6,000 young, ornamental maple, magnolia and cherry trees.

The city's park board said in a news release the first two years of a tree's life are vital to its survival and it's rare for the city to be in the situation it is currently facing so early in the summer.

Five trucks, two of which are pulling double shifts, are already watering the trees.

"Watering could even become a family activity and a great opportunity to teach children about the importance of trees," said John Coupar, park board chairman.

On Vancouver Island, a low streamflow advisory remains in place for many rivers. The River Forecast Centre is blaming a low snowpack, warmer-than-average temperatures and below-normal precipitation.

The centre notes current river flows resemble late-August conditions and many are approaching or are below average-annual flow levels.