The fog arrived overnight and stayed through much of the morning. Commuters around the Valley had to take it slow on the roads.
Along Highway 99 in Selma, Cal Trans had their new fog warning system on to tell drivers about the dangerous conditions.
Despite the fog, most flights out of Fresno's airport escaped significant delays. One American Airlines departing flight to Los Angeles was cancelled, but the flight status board showed all other flights were on time.
Visibility at the airport was about a quarter mile.