Blue skies at last on B.C.'s south coast

People on B.C.’s south coast who’ve been hiding in air-conditioned buildings could see a blue sky as soon as Thursday.

According to Environment Canada meteorologist Lisa Erven, the wildfire smoke from the interior is expected to vacate by the weekend.

“In the next 24 hours, we’re going to see a wind reversal,” Erven said. “But it will take 24-48 hours to really clear out. Vancouver Island and the Lower Mainland have been fairly saturated.”

McNeill Bay today with heavy smoke due to ongoing wildfires around B.C. (Keri Coles/Oak Bay News))

An air quality advisory has been in place for the Lower Mainland since Aug. 13 because of fine particulate matter expelled by wildfires around the Pacific Northwest.

Erven said a trifecta of westerly winds, a high-pressure ridge and an abundance of wildfire smoke culminated in record-poor air quality for the region.

“There’s a ridge of high pressure providing a lid on the atmosphere,” she said, particularly in the Fraser Valley.

Different parts of the south coast have seen vastly different conditions, with places like Chilliwack beginning to resemble a post-apocalyptic world, while parts of Vancouver have seen some blue sky.

A blue sky in Vancouver, compared to smoky skies in Chilliwack. (Black Press Media)

“That’s again to do with location of wildfires and local winds. Wildfire smoke concentrations naturally carry wildly over short distances,” Erven said.

“A subtle change of the wind direction improves air quality locally and it can be quite different in North Vancouver, Tsawwassen and Abbotsford.”

By Thursday morning, the high-pressure ridge is set to break down as a cool front sweeps in, with highs of just 19 C until Sunday.

The Lower Mainland hasn’t seen such smoke since 2015, Erven said, when wildfires near Pemberton sent up thick clouds.

“Whistler’s air quality was very very poor through that time period,” she said. “But it’s not uncommon to get outflow conditions” that bring in wildfire smoke.