California, 2021

Dense Fog in California, January 16, 2021

January 16, 2021 · NWS HNX · 4 events in 4 counties and zones

With high pressure remaining over central California, areas of fog reformed during the early morning hours of January 16 reducing visibility to as low as 500 feet in the center portion of the San Joaquin Valley along the State Route 99 corridor from State Route 198 northward. The fog dissipated by late morning.

The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
4

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 high pressure remaining over central California, areas of fog reformed during the early morning hours of January 16 reducing visibility to as low as 500 feet in the center portion of the San Joaquin Valley along the State Route 99 corridor from State Route 198 northward. 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 Jan 15, 6:09 PM PST, 6 hours 56 minutes earlier.

Area forecast discussion, Jan 15, 6:09 PM PST, 6 hours 56 minutes before
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Event by event

4 dense fog. Local standard time, as filed.

Dense Fog, Tulare County

When
January 16, 1:05 AM PST to 2:50 AM PST
Where
Tulare County forecast zone
Reported by
AWOS

Visalia reported visibility below a quarter mile.

Dense Fog, Merced and Madera

When
January 16, 3:55 AM PST to 11:20 AM PST
Where
Merced and Madera forecast zone
Reported by
ASOS

Merced and Madera reported visibility below a quarter mile.

Dense Fog, Fresno

When
January 16, 4:10 AM PST to 8:15 AM PST
Where
Fresno forecast zone
Reported by
ASOS

Fresno reported visibility below a quarter mile.

Dense Fog, Foggy Bottom

When
January 16, 5:55 AM PST to 7:35 AM PST
Where
Foggy Bottom forecast zone
Reported by
ASOS

Hanford 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 2026-10-01. Each event’s entry at NCEI: 929307, 929304, 929306, 929305.