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San Francisco Bay Area residents awoke to darkened orange and yellow skies on Wednesday morning, as smoke from fires raging across California and the West rose into the upper atmosphere and blotted out the sun.
This tweet from the National Weather Service explains what's happening:
Contributing to the smoke was the Northern California Bear Fire, which grew extremely rapidly overnight:
The Creek Fire, which started Friday, has burned more than 163,000 acres east of Fresno and is 0% contained. Fires in Oregon and Washington are also contributing to the unusual conditions.
The Bay Bridge seen through a thick haze of smoke
The Bay Bridge is seen under an orange sky darkened by the smoke from California wildfires in San Francisco, California, U.S., September 9, 2020.
Stephen Lam | Reuters
View of Oracle Park
September 9, 2020; San Francisco, California, USA; General view of Oracle Park before the game between the San Francisco Giants and the Seattle Mariners.
Kyle Terada | USA TODAY Sports | Reuters
Mid-day streetlights and cars with headlights on in San Francisco
At 11 a.m. on Sept. 9 in San Francisco, the sky was so dark from distant smoke that streetlights turned on and cars drove with headlights on.
Salvador Rodriguez | CNBC
Russian Hill in San Francisco
Streetlights, headlights, and apartments with lights on around noon on Sept. 9, 2020, in Russian Hill, San Francisco.
Christina Farr | CNBC
YouTube headquarters
YouTube headquarters around noon on Sept. 9, 2020, under skies darkened by smoke from wildfires across the west.
CNBC
Streetlights in San Bruno, near San Francisco International Airport
Streetlights are on in the middle of the day in San Bruno, Calif., as the sky is darkened by smoke from fires across the west.
CNBC
A Tesla under smoke-darkened skies in San Francisco
An orange glow suffuses this San Francisco street as wildfire smoke fills the atmosphere on Sept. 9, 2020.
Jordan Novet | CNBC
Smoke from wildfires envelops San Francisco skyscrapers
The Transamerica Building in San Francisco darkened by orange-colored smoke high in the atmosphere, several hours after sunrise on Wednesday, Sept. 9.
Photo By Victor Vu
The smoke in the upper atmosphere blots out the sun
Smoke in the upper atmosphere turns the sky near the Coit Tower in San Francisco an eerie orange on Wednesday morning, Sept. 9.
Photo: Victor Vu
The sky in Oakland
The sky in Oakland was dark orange from high-atmosphere wildfire smoke on Wednesday morning, Sept. 9.
Kif Leswing | CNBC
Flames from the Bear Fire
A law enforcement officer watches flames launch into the air as fire continues to spread at the Bear fire in Oroville, California on September 9, 2020.
Josh Edelson | AFP | Getty Images
Lake Oroville during the Bear fire
A boat motors by as the Bidwell Bar Bridge is surrounded by fire in Lake Oroville during the Bear fire in Oroville, California on September 9, 2020.
Josh Edelson | AFP | Getty Images
Firefighters monitor the Bear Fire
Butte County firefighters watch as flames quickly spread across a road at the Bear fire in Oroville, California on September 9, 2020.
Josh Edelson | AFP | Getty Images
A vehicle streaks by the Creek Fire
A vehicle streaks by in a long exposure as Fresno County Sheriff Deputy Jeffery Shipman stands along CA-168 as the Creek Fire creeps closer to town on Sunday, Sept. 6, 2020 in Shaver Lake, CA.
Kent Nishimura | Los Angeles Times | Getty Images
Laguna Hotshots battle the Creek Fire
The Laguna Hotshots Crew out of the Cleveland National Forest battle the Creek Fire as it approaches the Souther California Edison Big Creek Hydroelectric Plant on Sunday, Sept. 6, 2020 in Big Creek, CA.
Kent Nishimura | Los Angeles Times | Getty Images
Residents await evacuation
Kelsey Mueller, 16, pets Ruby while waiting with her family to be escorted from the evacuation zone at the Shaver Lake Marina parking lot off of CA-168 during the Creek Fire on Monday, Sept. 7, 2020 in Shaver Lake, CA.
Kent Nishimura | Los Angeles Times | Getty Images
Scorched vehicles from the Creek Fire
Burned vehicles smolder at a residence during the Creek fire in an unincorporated area of Fresno County, California on September 08, 2020.
Josh Edelson | AFP | Getty Images
Exhausted firefighters taking a break from battling the Creek Fire
Firefighters (L to R) Rob Spitzer, Max Kitty, Josiah Gist, and Hunter Grossmann with Cal Fire Madera Mariposa Merced Unit - Rancheria takes a break along Waterfall Way in the Cascadel Woods community where he and his colleagues have been fighting the Creek Fire since Saturday , photographed on Tuesday, Sept. 8, 2020 in Madera County, CA.
Kent Nishimura | Los Angeles Times | Getty Images
Smoke over Yosemite National Park on Saturday
Smoke from the Creek Fire settles over Half Dome and Glacier Point in Yosemite National Park, California, U.S., on Saturday, Sept. 5, 2020.
Naureen Malik | Bloomberg | Getty Images