This image comes from the US Forest Service MODIS satellite imagery and was taken just a few hours ago, August 23, 2013
San Francisco is near the lower center and the Yosemite/Hetch Hetchy/Rim fire is the big smoke plume to the right. The smoke goes north through Lake Tahoe and Reno, Nevada. A map of the fire with Google Earth KML can be found here. The last time northern California had fires of this size was 2008 and you can see that image here
