Stagnant weather in the San Joaquin valley thanks to a large area of high pressure over California.
Cold air sinks to the bottom of the valley, causing frost and patchy dense fog.
A dense fog advisory was issued for Sunday morning.
While afternoons will be sunny with above-average highs.
Temperatures will be cooler, again, by the end of the week. There’s a slight chance of rain and high mountain snow going into next weekend.