Smoke from fires in the U.S. began wafting into the Okanagan on Friday morning, dimming skies on the eve of the August long weekend.

Smoke from wildfires in Washington State will cloud Okanagan skies today and degrade air quality.

The August long weekend is shaping up to present a mix of smoke-tinged skies and thunderstorm warnings, but with temperatures sizzling enough to prompt a heat advisory.

"Overall, I think it's still going to be a pretty nice weekend," Environment Canada meteorologist Doug Lundquist said Friday morning.

"It's the pre-eminent weekend of the summer, and at least we're not looking at a lot of rain," Lundquist said.

Smoke from fires in California, Oregon, and Washington State began wafting into the Okanagan on Friday morning. Air quality was rated a 2, or low risk, but conditions were expected to degrade to a reading of 4, or moderate risk, later Friday and into Saturday.

At a moderate air quality risk, people with heart or breathing problems should consider rescheduling strenuous outdoor activities. And even healthy people should consider this if they experience symptoms such as coughing or throat irritation.

A somewhat more optimistic outlook for weekend smoke conditions is provided by the website FireSmoke.Ca

On Friday morning, it showed much of the Okanagan enveloped in light smoke, but the site predicts shifting winds will clear skies overnight. It forecasts no smoke over the Okanagan on Saturday or Sunday.

A smoky start to the August long weekend will be of concern to members of the tourism industry, who are already dealing with diminished revenues this year because of the months-long coronavirus pandemic.

And a surge in local COVID-19 cases, linked mostly to large parties held around Kelowna over the Canada Day holiday, also has the potential to deter some tourists.

"With hot summer weather, increased wildfire risk, and additional COVID-19 public health measures, we must take extra care of ourselves, each other, and our destination," says Lisanne Ballanytne, president of Tourism Kelowna.

"We ask everyone to come prepared, take their time, give others space, and be mindful of their activities so we can all continue to enjoy our favourite summer activities," Ballantyne said.

As of Friday, Environment Canada's long weekend forecast for the Okanagan called for sunny or mainly sunny skies with highs of between 32-34 C on Saturday and Sunday, and 27 C on Monday. A heat warning was issued for Friday, when temperatures had been expected to reach 35 C. But there was also said to be "widespread risk" of thunderstorms across the BC Interior, with the potential for lightning strikes to ignite wildfires.