The city by the Bay is resembling a city on Mars.
"Unprecedented amount of smoke in the atmosphere as a record number of acres burn across California & the West," the NWS tweeted.
A massive cloud of smoke covered much of California on Wednesday, dimming the sun to an eerie orange glow over San Francisco.
"Extremely dense & tall smoke plumes from numerous large wildfires, some of which have been generating nocturnal pyrocumulunimbus clouds ('fire thunderstorms), are almost completely blocking out the sun across some portions of Northern California this morning," UCLA climate scientist Daniel Swain wrote on Twitter.
The Bay Area Air District said in series of tweets that strong winds over the past few days transported ash from fires in northern California and the Sierra Nevada into the region.
"These smoke particles scatter blue light & only allow yellow-orange-red light to reach the surface, causing skies to look orange," the agency said. "If smoke becomes too thick in a certain area, most of the light will be scattered & absorbed before reaching the surface, which may cause dark skies."
Photos from around the Bay Area showed wildfire smoke obscuring the sky.
Many cars were driving around with headlights, and office towers had their lights on.
The Air District extended a "Spare the Air Alert" through Wednesday due to the smoke in the air.
“The Labor Day weekend heatwave, combined with tailpipe exhaust and lingering wildfire smoke, is expected to cause unhealthy air quality in the region,” Jack Broadbent, executive officer of the Air District, said in a statement. “Driving less can help reduce smog and heading indoors when smoke is present can help protect our health.”
On Tuesday, the Bay Area hit a new record of 22 consecutive days of Spare the Air alerts due to the smoke from the blazes since August, KTVU reported.
The worst air quality readings were in Napa, Concord, Livermore, Pleasanton, Gilroy, and San Jose. Those areas had unhealthy levels for sensitive groups for most of the day and at times were hazardous.
Photos and videos posted to Twitter show the extent of the orange skies throughout the region.
More than 14,000 firefighters are battling fires in California. Two of the three largest blazes in state history are burning in the San Francisco Bay Area, though they are largely contained after burning for three weeks.
Winds have fanned a huge fire in the Sierra Nevada foothills and forced authorities to order early morning evacuations and warn other residents to be ready to leave.
The state has set a record with nearly 2.3 million acres burned this year and the worst part of the wildfire season is only beginning.
“It’s extraordinary, the challenge that we’ve faced so far this season,” Gov. Gavin Newsom said on Tuesday.
The Associated Press contributed to this report.