California, 2021

Dense Fog in California, January 1, 2021

January 1, 2021 · NWS HNX · 3 events in 3 counties and zones

With the frontal system which pushed through the area on December 31 moving out of the area by the morning of January 1, clearing skies and light winds allowed for an area of dense fog to form overnight in the center of the San Joaquin Valley between Lemoore and Visalia which briefly impacted travel along State Route 198. The fog dissipated by late morning.

The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
3

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.

With the frontal system which pushed through the area on December 31 moving out of the area by the morning of January 1, clearing skies and light winds allowed for an area of dense fog to form overnight in the center of the San Joaquin Valley between Lemoore and Visalia which briefly impacted travel along State Route 198. The fog dissipated by late morning.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Hanford, CA wrote its last area forecast discussion before the first event at Dec 31, 2:50 PM PST, 13 hours 35 minutes earlier.

Area forecast discussion, Dec 31, 2:50 PM PST, 13 hours 35 minutes before
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Event by event

3 dense fog. Local standard time, as filed.

Dense Fog, Foggy Bottom

When
January 1, 4:25 AM PST to 9:10 AM PST
Where
Foggy Bottom forecast zone
Reported by
ASOS

Hanford reported visibility below a quarter mile.

Dense Fog, Tulare County

When
January 1, 4:55 AM PST to 8:25 AM PST
Where
Tulare County forecast zone
Reported by
AWOS

Visalia reported visibility below a quarter mile.

Dense Fog, Western San Joaquin Valley

When
January 1, 7:23 AM PST to 10:27 AM PST
Where
Western San Joaquin Valley forecast zone
Reported by
ASOS

Lemoore reported visibility below a quarter mile.

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, January 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: 927123, 927124, 927122.