The orange hue is caused by wildfire smoke in the air, according to the Bay Area Air District.
“These smoke particles scatter blue light & only allow yellow-orange-red light to reach the surface, causing skies to look orange,” the Air District explained in a tweet. “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: Here’s a look at the sky from different places in the Bay Area
KRON meteorologist John Shrable says smoky air is coming into the area from wildfires burning in Northern California.
Smoke in some cases is sitting right above a thin marine layer at the surface with the veil of fog making for an even more ominous look.
While some places are lit up in bright red and orange, others are seeing a smokier, ashy gray sky.
There are also reports of ash all over the region, as a viewer photo from Alama shows.
The Air District noted that the ash from wildfires from the central and northern part of the state, including the Sierra Nevada, have been transported by strong winds to the Bay Area over the past few days.
The National Weather Service Bay Area tweeted that some ash falling is larger than the width of human hair, while finer particles stay suspended in the air.
Air quality in the Bay Area is a concern, especially with potential to breathe in these ash particles. While gyms are allowed to reopen Wednesday in San Francisco with outdoor-only workouts — the smoky air may make people want to skip physical activity for the day.