Fog in the Weather Picture

For the second day in a row, dense fog rolled into parts of Los Angeles County from the Pacific, limiting visibility along the coast to a quarter-mile or less by nighttime, the National Weather Service said.

While many areas enjoyed a clear, crisp autumn afternoon, the fog caused traffic delays of about an hour at Los Angeles International Airport, and 14 flights were diverted to Ontario International Airport, an airport spokeswoman said.

Early Monday, one of the heaviest fogs in years halted shipping for about five hours in the ports of Los Angeles and Long Beach, the third-largest harbor complex in the world. The lack of visibility prompted both ports to prohibit ships from leaving and entering the harbor between 6 and 11 a.m. About 20 vessels were affected, including two arriving cruise ships, according to the Marine Exchange, which tracks ships in the Harbor area.

“This is the worst fog I have ever seen,” said Richard Wieneke, a watch supervisor who has worked 14 years at the Vessel Traffic Information Service of the Marine Exchange.

But a combination of relatively warm days and cool but not freezing nights has enhanced the array of reds, yellows and oranges speckling autumn foliage this weather officials said, weather officials said.