Thursday's high temperatures in the Seattle-Olympia area are expected to be 12 to 17 degrees Fahrenheit cooler than today's.
The National Weather Service issued air quality alerts for much of Washington state as well as parts of northern Idaho until late Wednesday, but the levels are expected to improve through Thursday night and into Friday.
Photos of the smoke-choked Seattle skyline circulated on social media earlier this week as residents and tourists gawked at the poor air conditions. "Most of the haziness we're seeing is just this residual smoke".
Environment Canada said the index for Calgary was calculated as a 10 - very high risk - at 4 a.m., but it had dropped to 7 - high risk - by 8 a.m.
More than 2,000 evacuees headed to Prince George after being ordered out because of an 850-square-kilometre blaze threatening an area from Fraser Lake to Fort St. James.
City officials said all Riverfront Park attractions closed Monday due to the hazardous air quality, and some garbage and recycling pickup would be delayed until at least Tuesday.
"We have serious challenges for public health and we need to adapt our policy making, working with all levels of government to make sure that as we go forward we're better prepared", said Horgan, flanked by federal Defence Minister Harjit Sajjan, Mayor Lyn Hall and Grand Chief Ed John of the First Nations Summit.
In the United States, smoke from wildfires also clogged the sky across the west, blotting out mountains and city skylines from OR to Colorado, delaying flights and forcing authorities to tell even healthy adults in the Seattle area to stay indoors. The reduced visibility also posed a problem for crews working to bring the wildfires under control. "And that's kind of allowed the smoke to persist", he said.
"We're getting finally a change in the air mass and actually that change is here to stay well through the weekend and into the beginning of next week", Meteorologist with Environment Canada Matt McDonald said.
Forecasts were calling for winds to pick up speed in the area Tuesday and Wednesday. Officials said an increase in wildfire activity in southeastern B.C. was also a concern.