SEATTLE — Wildfire smoke drifting across the ocean from Siberia to the Pacific Northwest may explain why Seattle has had so many spectacular sunsets recently.

Dozens of wildfires on Russia’s east coast have burned hot enough to lift the smoke high into the air, where it gets caught in the jet stream, scientists say. It’s then carried across the ocean to the Pacific Northwest, the Seattle Times reported.

Cliff Mass, a professor of atmospheric sciences at the University of Washington, said the smoke isn’t a health risk but may be the reason behind the recent series of spectacular sunsets.

“It’s fading now a little bit, but the fires are not over,” he said. The smoke has lessened over Seattle in the last few days but didn’t prevent a vivid sunset on Thursday, he added.

“We always see some level of smoke and pollution” from East Asia, Dan Jaffe, a professor of atmospheric and environmental chemistry at UW Bothell told the Times. It’s especially common in the springtime.

But the smoke that has drifted here in the last two weeks is the worst since 2003, Jaffe said.

It’s fed by huge fires burning near Lake Baikal and on the Kamchatka Peninsula on Russia’s east coast. Last week, 67 wildfires were burning in Eastern Russia, according to RIA Novosti, a Russian state news agency.

Lyatt Jaeglé, a UW professor who has studied how pollutants travel long distances, said the smoke gets caught in the jet stream, which carries it to the Pacific Northwest. The high pressure of the past week here has helped bring the smoke to the ground, he added.

The course of the jet stream makes the Pacific Northwest the front line for East Asian pollution on the West Coast.

Meteorologists have observed the smoke of the last two weeks from British Columbia down to Oregon, where Jaffe has monitored it from his research station on Mount Bachelor, near Bend.

It takes about seven to 10 days, said Eric Taylor, an air-quality meteorologist with the Ministry of Environment in British Columbia, which has also seen smoky skies recently.

Smoke, dust and other pollutants from across the Pacific don’t usually make it too far inland.

“A lot of this stuff is taken out by the Cascades and the Rockies,” Mass said.

The haze in British Columbia has mostly affected the coastal area near Vancouver, but some pollutants have made it across the mountains into the province’s interior.

“It seems that this smoke bloom from Siberia also carried with it a lot of ozone,” Taylor said.

Air quality, however has remained normal in the Seattle area, Phil Schwartzendruber, an air-resources specialist with the Puget Sound Clean Air Agency, told the Times.

Fireworks on the Fourth of July in some Seattle neighborhoods hurt the air quality more than the smoke has, he said.

Low-pressure systems and rainy days would help combat the smoke, but it could return as long as the fires continue to rage.