Some even went so far as canceling buses altogether.
At Fowler Unified, all sixteen buses stayed parked in the yard for the second day in a row.
"For me, the fog is the scariest time," said Javier Moreno, the director of maintenance, operations and transportation for Fowler Unified.
Last year, the district had just two foggy day schedules for the entire year.
Now, it's already on track to beat that - before winter even begins.
Moreno and his spotters wake up extra early to be out on the road by 5am to make the call on whether or not to set back the start school.
The district has several plans in place depending on fog density, going as far as cancelling all buses.
"Plan A sets us back two hours we come out and do a fog check. Typically, we go out and do survey areas. If you need to, we'll go to Plan B, which has another hour now we're delayed three hours," said Moreno.
For Fowler, Wednesday is normally an early release day, but because of the foggy start schools had to return to normal release to make up for the hours lost in the classroom.
Attendance is also a huge issue for the district as many students just stay home.
Scattered fog can be frustrating for parents, but Moreno says his staff will not take any chances.
"Sometimes parents are like well, it's not that foggy today, but it could be foggy in another area. Not taking that risk of our bus drivers with students," says Moreno.
Lorraine Acosta, the transportation lead for Fowler Unified, has been driving students for decades but says no amount of experience guarantees safety driving in the fog.
"We look and listen and we're hoping that everyone has their lights on and nowadays everyone drives extremely fast. Everyone's in a hurry all the time," said Acosta.
Rural bus drivers are trained to read road lines and pull over if they feel unsafe.
Each bus is also equipped with special fog safeguards like strobe lights on top of the bus.
With lives at her fingertips, Acosta says she takes her huge responsibility seriously.
"I couldn't live with myself if something were to happen just because we needed to bring a child into school. Safety is number one. That yellow bus that's what it's all about safety," said Acosta.
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