California, 2021

Dense Fog in California, November 20 to 21, 2021

November 20 to 21, 2021 · NWS HNX · 10 events in 10 counties and zones

Low level upslope resulted in dense fog forming in the Tehachapi area during the evening of November 20. An offshore wind developed and resulted in downslope winds which dissipated the fog by late evening.

Where it happened

Every event with a place to put it; 10 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

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The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
10

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS HNX wrote it up.

Low level upslope resulted in dense fog forming in the Tehachapi area during the evening of November 20. An offshore wind developed and resulted in downslope winds which dissipated the fog by late evening. Meanwhile, clear skies, light winds and inversion conditions resulted in widespread dense fog forming in the San Joaquin Valley during the evening of November 20 into the early morning of November 21. The fog persisted over a widespread area until late morning when it lifted into a low clouds deck which eroded during the early afternoon.

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

10 dense fog. Local standard time, as filed.

Dense Fog, Tehachapi

When
November 20, 6:35 PM PST to 9:35 PM PST
Where
Tehachapi forecast zone
Reported by
AWOS
Coordinates
35.343, -118.730 (the zone’s center; the record gives no point)

Visibility below a quarter mile was reported in Tehachapi.

Dense Fog, Visalia - Porterville - Reedley

When
November 20, 8:50 PM PST to November 21, 11:05 AM PST
Where
Visalia - Porterville - Reedley forecast zone
Reported by
AWOS
Coordinates
36.489, -119.224 (the zone’s center; the record gives no point)

Visibility below a quarter mile was reported in Visalia and Porterville. Several webcams showed visibility below 1000 feet.

Dense Fog, Hanford - Corcoran - Lemoore

When
November 21, 12:45 AM PST to 11:05 AM PST
Where
Hanford - Corcoran - Lemoore forecast zone
Reported by
ASOS
Coordinates
36.351, -119.421 (the zone’s center; the record gives no point)

Visibility below a quarter mile was reported in Hanford. Several webcams showed visibility below 1000 feet.

Dense Fog, Delano - Wasco - Shafter

When
November 21, 12:55 AM PST to 9:55 AM PST
Where
Delano - Wasco - Shafter forecast zone
Reported by
AWOS
Coordinates
35.879, -119.115 (the zone’s center; the record gives no point)

Visibility below a quarter mile was reported in Delano. Several webcams showed visibility below 1000 feet.

Dense Fog, Bakersfield

When
November 21, 5:30 AM PST to 9:15 AM PST
Where
Bakersfield forecast zone
Reported by
ASOS
Coordinates
35.343, -118.730 (the zone’s center; the record gives no point)

Visibility below a quarter mile was reported in Bakersfield. Several webcams showed visibility below 1000 feet.

Dense Fog, Buttonwillow- Lost Hills - I5

When
November 21, 5:30 AM PST to 10:00 AM PST
Where
Buttonwillow- Lost Hills - I5 forecast zone
Reported by
Department of Highways
Coordinates
35.709, -119.273 (the zone’s center; the record gives no point)

Several webcams showed visibility below 1000 feet.

Dense Fog, West Side of Fresno and Kings Counties

When
November 21, 6:31 AM PST to 9:56 AM PST
Where
West Side of Fresno and Kings Counties forecast zone
Reported by
ASOS
Coordinates
36.417, -119.732 (the zone’s center; the record gives no point)

Visibility below a quarter mile was reported in Lemoore. Several webcams showed visibility below 1000 feet.

Dense Fog, Merced-Madera-Mendota

When
November 21, 6:40 AM PST to 10:25 AM PST
Where
Merced-Madera-Mendota forecast zone
Reported by
ASOS
Coordinates
37.056, -120.043 (the zone’s center; the record gives no point)

Visibility below a quarter mile was reported in Merced. Several webcams showed visibility below 1000 feet.

Dense Fog, Los Banos-Dos Palos

When
November 21, 6:45 AM PST to 10:00 AM PST
Where
Los Banos-Dos Palos forecast zone
Reported by
Department of Highways
Coordinates
36.975, -120.184 (the zone’s center; the record gives no point)

Several webcams showed visibility below 1000 feet.

Dense Fog, Caruthers - San Joaquin - Selma

When
November 21, 6:45 AM PST to 10:00 AM PST
Where
Caruthers - San Joaquin - Selma forecast zone
Reported by
Department of Highways
Coordinates
36.489, -119.224 (the zone’s center; the record gives no point)

Several webcams showed visibility below 1000 feet.

What these are

Dense Fog
Fog reducing visibility to a quarter mile or less, filed where it caused accidents or disruption.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, November 2021

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 2026-09-30. Each event’s entry at NCEI: 985885, 985886, 985889, 985891, 985890, 986068, 985888, 985887, 986065, 986066.