Smoke from BC wildfires likely to drift into Calgary later this week

Calgary's air quality cleared Tuesday after smoke from Northwest Territories wildfires drifted through, but residents should prepare for another air quality dip later this week as winds shift and bring smoke from fires burning in British Columbia.

The air quality index in Calgary spiked to 7 on Tuesday morning but surface-level winds helped disperse the smoke throughout the day. Northern Alberta cities including Edmonton weren't as fortunate — Edmonton's air quality index reached 9, considered high risk, prompting health officials to urge residents with respiratory sensitivities to consider reducing or rescheduling strenuous outdoor activities.

"Now our winds have shifted," said Janelle Gergely, meteorologist at Environment Canada. The shift means Calgary will soon receive air from the Pacific Northwest, which will bring warmer temperatures alongside smoke from fires burning in British Columbia. The change is driven by Rossby waves — movements of the Earth's atmosphere that influence the jet stream, which marks the separation between warmer and colder air masses.

As of Tuesday, four wildfires are spiralling out of control in BC. Three are blazing west of Kimberley, prompting evacuation orders for roughly 9,000 nearby residents. A large fire near Boston Bar, an unincorporated community along Highway 1 in the Fraser Canyon about 45 kilometres north of Hope, has sparked multiple evacuation orders and alerts.

Predicting exactly when and how much smoke will affect Calgary is challenging, Gergely cautioned. "If all the fires went out, which they likely won't, then we wouldn't see the smoke. So really, all I can say is there's the possibility that smoke could be moving over the Rockies from a different source."