Flight-Delaying Fog Out--but Traffic Rolling In : Travel: Clearing today comes in time for the start of the holiday rush at John Wayne Airport, highways.

COSTA MESA —  Forecasters say the thick morning fog that caused delays at John Wayne Airport for the third straight day Tuesday is over, just in time for holiday travelers to start packing the airport and freeways.

“This year is kind of funny since Christmas is on a Sunday,” said Bonnie Koch, owner of El Camino Travel in San Clemente. “The heaviest travel will be the Friday before Christmas. . . . There are a lot of functions going on (Monday, Jan. 2) and everybody has to go back to work on (Jan. 3), so Monday’s going to be a busy day too.”

Last year, from Dec. 20 to Jan. 3, a total of 280,093 people flew in and out of John Wayne. This year, more than 300,000 are expected for the same period, said Pat Ware, spokeswoman for John Wayne Airport. Last year, when Christmas fell on a Saturday, the heaviest flying days were Wednesday and Thursday, with about 23,000 passengers using the airport each day, she said.

On Tuesday morning, dense, patchy morning fog delayed flights for more than an hour. The fog lifted about 8:30 a.m., but not soon enough for passengers on a dozen flights whose takeoffs and landings were delayed.

Airport officials are optimistic that travelers won’t be affected today.

“The weather forecast looks like rain, and fog doesn’t come with rain,” Ware said. “Flights should not be affected since rain does not cause nearly as much of a visibility problem as fog does.”

An offshore flow kicking in early Monday night drove fog away early Tuesday, and a 40% chance of rain is forecast this afternoon and tonight with clearing Thursday. A chance of rain is also expected Saturday, with Christmas Day being partly cloudy, said Curtis Brack, a forecaster with WeatherData, which provides forecasts for The Times.

Highs will be in the 60s to low 70s, and lows will be in the upper 30s to mid 50s, Brack said.

Travel agents said weather has not had a big effect on their clients, many of whom bought tickets in the fall when some airlines were engaged in a price war.

“Air fares have been so low,” said Dianne LaPort, vice president of operations for World Travel, which has 15 locations throughout Orange County and the Inland Empire.

John Wayne Airport will be particularly busy this year because the May and November additions of Southwest Airlines and Reno Air have increased the options for travelers, Ware said. The airport now has 11 commercial airlines.

Though the fog might not cause delays, airport officials are urging travelers to account for the crowds by arriving at least 1 1/2 hours early.

Long-term parking is expected to fill by Thursday, so motorists are advised to park at a remote 1,679-space area on Main Street between MacArthur Boulevard and Red Hill Avenue. A free shuttle will be available to take passengers to terminals, Ware said. More than 300 hourly parking spaces are also available immediately in front of the terminal for people picking up family and friends.

Skies may be clear, but roads may also be slick from rains. California Highway Patrol officers urge people to be cautious, check vehicles before setting off, leave plenty of room between each vehicle and avoid drinking and driving.

Police will be out in force too.

“What we have starting Friday are maximum enforcement periods,” which includes drunk-driver checkpoints, said Officer Joan Rivas, a spokeswoman for the California Highway Patrol in Westminster.

Freeways with the most traffic will be those that lead out of the county, such as the San Diego Freeway and the Santa Ana Freeway, said Kari Keul, spokeswoman with the Orange County Traffic Management Center in Santa Ana.