High pressure built over central California on January 5. With mainly clear skies and light winds, areas of dense fog formed in the San Joaquin Valley during the early morning hours of January 6.
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.
The episode as NWS HNX wrote it up.
High pressure built over central California on January 5. With mainly clear skies and light winds, areas of dense fog formed in the San Joaquin Valley during the early morning hours of January 6. The fog did cause a few automobile accidents as it formed over a widespread area. The fog lifted into a stratus deck by late morning as a weak system moved through northern California then dissipated by midday.
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 5, 4:32 PM PST, 8 hours 3 minutes earlier.
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</html>7 dense fog. Local standard time, as filed.
Merced and Madera reported visibility below a quarter mile. At 0050 PST, a two car collision took place in Madera with California Highway Patrol reporting visibility below 1000 feet at the time. A chain link fence was damaged due to the collision, but there were no injuries.
Fresno and Reedley reported visibility below a quarter mile. A trained spotter in Sanger reported 125 foot visibility at 0900 PST.
Lemoore reported visibility below a quarter mile.
Visalia and Porterville reported visibility below a quarter mile.
Hanford reported visibility below a quarter mile. A four vehicle accident took place on SR 198 at 0809 PST involving a big rig, a pickup truck and two cars. There was minor injury from the collision and visibility at both Hanford and Visalia was at an eighth of a mile at the time of the accident.
Delano reported visibility below a quarter mile.
California Highway Patrol reported a semi truck struck a power pole at 0907 PST in heavy fog at the intersection of Rowlee Rd and Kimberlina Rd west of Wasco. The truck driver had minor injuries and the power pole was on fire after the collision.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, January 2021
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. Each event’s entry at NCEI: 927829, 927832, 927830, 927833, 927831, 927834, 927835.