Ugly is an understatement. I can only speak as to the Camp fire, but thursday the skies were black, streetlights on, etc.
Ash raining started late thursday night, I had to evac and watch the news remotely. 99 closed (it was open when I left, closed when I got to the first light in Chico with the flames right there at the side of the road), 32 impacted, I had to take a back road to 45 and then 162 over to 5, even as far as willows (where I got the news the fire had jumped 99) and other towns on that route and my whole drive down 5 I could see the ash raining. Official estimates today are 100k acres, 20% containment and probable high winds that will undo that. According to the Sheriff: An Evacuation Warning has been issued for East Bound Hwy 162/Oro Quincy Hwy at Canyon Creek Bridge east to Mountain House Road, including the communities of Berry Creek, Brush Creek, Mountain House, and Bloomer Hill.
It's not just also threatening Chico and Oroville, but its also threatening the rail and the water reservoirs, it's currently looking like the water quality for a few towns in Butte will be heavily impacted if the fire gets to the reservoir. Paradise had been evacuated to chico, now everyone is getting a majorly roundabout evacuation to Oroville. Other centers I believe were as far as Yuba City, which instead of having ash raining when I was there was just horrifically smoky.
The last one I really dealt with was the cedar fire and frankly this one has been far worse already.