Cool and dry weather pattern will continue into next week with morning Valley fog. Chance of light precipitation returns around Tuesday for portions of NorCal.

Cool and dry weather across interior NorCal today, Saturday, December 17.


Fog has been slow to lift today over the Northern San Joaquin Valley with vis at Stockton and Modesto just improving to 1 sm or better during the past hour. Elsewhere, sunny and cool conditions with temperatures gradually climbing towards the mid and upper 50’s at Valley locations.

Expect widespread fog to once again develop tonight into Sunday morning as depicted by latest HREF guidance, which has dense fog probabilities over a larger area versus last night. Have reissued dense fog advisory for tonight for the Southern Sacramento, Northern San Joaquin Valley and Delta in line with HREF from 11pm to 11 am.

Upper ridge over the eastern Pacific will remain in control of the Northern California weather through Monday, then a weak system will drop southeast over the ridge Monday and Tuesday with a few very light showers possible with maybe 1 or 2 inches of snow over the Sierra with snow levels above 4,000. This system is likely to continue trending drier given that it is moving from the northwest in a rather dry flow regime.

Morning lows will continue on the cold side near freezing at many Valley locations through Monday warming to the mid/upper 30’s Tuesday.

Holiday Travel Outlook, Interior Northern California December 17-25, 2022. Sat 17 – Mon 19, impact: None, Morning fog and frost. Tue 20, impact: Minor, Slight chance for mountain rain & snow showers. Wed 21, impact: None, Partly cloudy. Thu 22 impact: minor, Slight chance for mountain rain & snow showers. Fri 23 – Sun 25, impact: none, Partly cloudy.

Extended Discussion (Wednesday through Saturday)

Upper-level ridge develops off the West Coast by the middle of next week, resulting in day-to-day warming throughout interior northern California. Some ensemble guidance suggests another chance of light precip by late Thursday/Friday, mainly for far northern California and the Sierra. Ensembles are trending drier with system with latest NBM/WPC guidance showing very little precipitation.