Dense Fog in California
Every dense fog event the National Weather Service has filed in California, year by year, with the most significant episodes. Fog reducing visibility to a quarter mile or less, filed where it caused accidents or disruption.
The most significant on the map
The most significant dense fog episodes in California.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
The record
- Events
- 2,441
- Deaths
- 94
- Injuries
- 740
- Damage
- $24 million
Every year
The most significant
Ranked by deaths, injuries, damage and size together.
- Dense Fog in California, December 11, 1997Patchy dense fog was a main contributing factor in a major chain reaction collision on northbound Interstate 5 near Lambert, CA, 17 miles south of downtown Sacramento. The crash involved 8 tractor trailers, 1 tanker truck, and 28 automobiles and small trucks.
- Dense Fog in California, November 14, 1998One of the states's worst multiple vehicle accidents occurred in dense fog beginning at 0850 PST Saturday, November 14.
- Dense Fog in California, January 13 to 15, 2015Light winds and clear skies allowed dense morning fog to develop for several days. Numerous car accidents occurred, including two multiple car crashes with fatalities.
- Dense Fog in California, February 5 to 6, 2002Dense Fog formation throughout the Central and Southern San Joaquin Valley occurred on both the mornings of the 5th and 6th.
- Dense Fog in California, November 3, 2007In the wake of the severe weather outbreak that hit the central and southern San Joaquin Valley on October 29th, there were pools of standing water in areas that received the heaviest rains.
- Dense Fog in California, November 14, 2020Dense fog developed across the Sacramento and northern San Joaquin Valleys on November 14 and 15. Visibility reports were generally below a quarter mile for most reporting stations, which lead to treacherous driving conditions during the overnight and morning hours.
- Dense Fog in California, January 14 to 15, 2024A small plane with four people onboard crashed near Moss Beach in San Mateo County, around 1 mile southwest of Half Moon Bay Airport, on January 14 at 7:34 PM. Witnesses saw the plane sputtering before the crash. Wreckage from the plane was found near Ross Cove.
- Flash Flooding and Flood in California, October 12 to 17, 2009A deep low pressure trough tapped into quite a bit of moisture from the remnants of Super-Typhoon Melor, bringing as much as around 2 inches of rain to the central and southern San Joaquin Valley on the 13th-14th. Much higher amounts fell in the Southern Sierra Nevada.
- Dense Fog in California, November 23 to 27, 2012A weak upper-level disturbance brushed the northern fringes of the WFO Hanford warning/ forecast area on November 20th-21st.
- Dense Fog in California, December 1 to 4, 2000Dense fog with visibility near zero contributed to several deadly motor vehicle accidents. One man was killed when his vehicle drove into an overpass abutment. Another was thrown from the vehicle as it ran off the road and he drowned in the nearby lagoon.
- Dense Fog in California, July 26, 2025A plane crash into the Pacific Ocean near Pacific Grove on July 26 killed all three people aboard. A twin-engine Beechcraft, tail number N8796R, departed from San Carlos Airport in the Bay Area at approximately 10:07 p.m., heading to Monterey Regional Airport.
- Dense Fog in California, December 30 to 31, 2016Synoptic high pressure moved over the central California region allowing for clear skies and dense radiational fog to develop over parts of the San Joaquin Valley.
- Dense Fog in California, December 3, 2021Little change in the upper air pattern occurred from the previous day. Clear skies, light winds and inversion conditions in the San Joaquin Valley allowed for areas of dense fog to form in Merced, Madera and Fresno Counties in the central San Joaquin Valley during the early…
- Dense Fog in California, January 6, 2024Some patches of dense fog formed in the south San Joaquin Valley during the morning of January 6.
- Dense Fog in California, February 9 to 12, 2008A tranquil weather pattern set in behind the storm from the 2nd and 3rd of February. An upper-level ridge of high pressure built into California on the 8th.
- Dense Fog in California, February 8, 2002Another multiple-vehicle accident caused by dense fog occurred on Highway 58 about 20 miles east-southeast of Bakersfield on the northwest slopes of the Tehachapi Mountains. About 40 vehicles were involved in 3 close proximity accident events starting at 10:30 AM PST.
- Dense Fog in California, December 24, 2014Moist conditions from recent rains couple with light winds brought areas of dense fog to the Central Valley and into the adjacent foothills. This caused minor car accidents and travel delays, especially affecting holiday travelers.
- Dense Fog in California, January 3, 2002Dense fog conditions east through south of Bakersfield and on the northern slopes of the Tehachapi Mountains led to instances of multi-vehicle accidents.
- Dense Fog in California, December 11, 1998Dense fog resulted in a multi-fatal accident 15 miles northeast of Stockton on Highway 88 at about 0410 PST.
- Dense Fog in California, January 28 to 31, 2015A storm system brought precipitation to central California on January 27, 2015, and was followed by an area of high pressure and stable conditions which led to dense fog development in the San Joaquin Valley each late night and morning on January 28-31.
- Dense Fog in California, January 12 to 17, 2026An impressive long lasting period of foggy conditions prevailed across the San Joaquin Valley from January 12th through January 31st (It continued through February 7th). Dense fog coverage increased for the next several days each morning starting on the 11th.
- Flash Flooding and Debris Flow in California, January 15 to 17, 2019A high impact mini atmospheric river impacted Southern California January 14th and 15th which brought heavy rain and snow to the region. Seal Beach reported 2 inches of rain in 2 hours, which caused extensive flash flooding.
- Dense Fog in California, January 15 to 16, 2022On the mornings of January 15th and 16th, dense fog developed over the central and southern Sacramento Valley and northern San Joaquin Valleys. Observation sites within in the area generally reported dense fog with visibility at or less than a quarter of a mile both mornings.
- Dense Fog in California, November 3, 2002Dense fog contributed to a major collision on Interstate 710 in Los Angeles county. In total, 194 vehicles were involved in the accident. Forty-one people were injured.
- Dense Fog in California, February 12 to 13, 2016Area of high pressure moved over the central California region creating favorable conditions for nighttime and early morning radiational fog development across the San Joaquin Valley.
More
Sources
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24.