An upper trough moved through California on January 22, scouring out the low stratus deck that had been over the San Joaquin Valley for several days. However, the trough was not strong enough to completely scour out the low level moisture. A ridge of high pressure over the eastern Pacific began to build into northern California creating stable conditions with good radiational cooling. This led to areas of dense fog developing just after midnight on January 23. Visibility improved above 1 mile as the fog lifted into a low stratus deck by noon and remained through the remainder of the day.
Dense fog redeveloped by early morning of January 24. The fog was particularly bad in Kern County where the California Highway Patrol reported areas of visibility less than 200 feet with pacing on many parts of Highway 99 and Highway 58 through Bakersfield. The fog once again lifted into a low stratus deck by afternoon. Then dense fog developed again late in the evening and persisted through noon on January 25. The fog lifted into a low stratus deck which persisted through the afternoon before clearing in the evening. This allowed areas of dense fog to redevelop in the early morning hours of January 26. This time, the dense fog was the worst on the west side of the San Joaquin Valley with visibility of 200 to 500 feet along parts of Interstate 5. The weather pattern began to change on January 26, allowing the fog to clear by mid morning as a low pressure system off the northern Baja coast began spreading clouds across central California and spreading some rain as far north as Kern county.

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 23-JAN-15 01:15:00 to 23-JAN-15 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Visibility 500 feet along highway 152 near Interstate 5.

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 22-JAN-15 23:35:00 to 23-JAN-15 11:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Widespread visibility less than 1/4 mile, including 1/8 mile reported at the Fresno airport causing airport delays.

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 24-JAN-15 02:17:00 to 24-JAN-15 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Areas of visibility less than 1/4 mile.

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 24-JAN-15 04:53:00 to 24-JAN-15 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Areas of visibility less than 1/4 mile near Hanford.

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 24-JAN-15 21:28:00 to 25-JAN-15 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Widespread visibility less than 1/4 mile.

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 25-JAN-15 07:53:00 to 25-JAN-15 09:45:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Widespread visibility less than 1/4 mile.

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 24-JAN-15 06:22:00 to 24-JAN-15 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Areas of visibility less than 1/4 mile. Areas of visibility less than 500 feet along Highway 99 through Madera and Merced counties.

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 24-JAN-15 19:35:00 to 25-JAN-15 09:45:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Widespread visibility less than 1/4 mile.

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 26-JAN-15 03:30:00 to 26-JAN-15 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Areas visibility less than 1/4 mile, including 200-500 ft visibility along Interstate 5.

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 26-JAN-15 08:00:00 to 26-JAN-15 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Areas visibility less than 1/4 mile.

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 26-JAN-15 04:23:00 to 26-JAN-15 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Areas visibility less than 1/4 mile.

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 23-JAN-15 01:15:00 to 23-JAN-15 09:02:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Widespread visibility less than 1/4 mile. CHP pacing on parts of Highway 99.

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 24-JAN-15 02:15:00 to 24-JAN-15 11:50:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Visibility less than 500 feet many areas along Highway 99 in Kern county, including Bakersfield.