Fog Delays 10 Flights at John Wayne : Weather: The mists also trapped leaking natural gas, forcing the evacuation of some homes. A lighter blanket is expected again today.

Thick morning fog delayed air travel at John Wayne Airport for 30 minutes Friday morning, while in Anaheim it slowed the dissipation of natural gas that had leaked from an underground pipe and caused the evacuation of several homes.

Steve Burback, a meteorologist with WeatherData Inc., which provides forecasts for The Times, said the fog was brought in by the breakdown of a high-pressure system over the desert that had persisted for more than two weeks. Santa Ana winds gave way to gentle breezes from the Pacific that brought in moisture from the sea.

Visibility was zero in some areas about 6 a.m. The mist affected nine departing flights and one arrival at John Wayne, airport spokeswoman Pat Ware said.

“The fog cleared up shortly after the airport opened” at 7 a.m., she said. “And everything then was back to normal.”

Forecasters predicted that the fog would return today but would be less dense.

In Anaheim, where city workers evacuated homes in the 800 block of Janss Stree, a backhoe operator trying to repair a water main accidentally punched a hole in an underground gas line, city spokesman Bret Colson said.

The 8 a.m. evacuation lasted two hours while workers plugged the 2-inch gas main. There were no injuries reported, he said.

Police and firefighters immediately evacuated five households while repair crews capped the leak, Colson said. However, another five homes also were evacuated when the dense fog prevented the gas from dissipating.

“It created an inversion layer,” Colson said. “The gas became trapped.”

Fire Department officials initially feared the leak would force evacuation of 1,000 children at Horace Mann Elementary School, about a block away. But the fog lifted before the gas reached the school grounds.

Forecasters predicted a return early this morning of a lighter version of the fog that had enveloped much of the coast late Thursday and early Friday, preventing planes from landing at Los Angeles International Airport for more than 15 hours.

Though John Wayne Airport was not closed, the blanket at the Los Angeles airport forced more than 20 inbound flights there to land at airports in Ontario, Burbank and even Las Vegas.

Burback said that by dawn today, the fog should start giving way to a low overcast that will increase with the approach of a low pressure weather system from the north. The weather front should pass through the area sometime tonight, bringing with it a slight chance of showers.

Gusting breezes from the northwest should leave skies clear by midday Sunday, with slightly higher temperatures.

Highs Friday in Orange County were mostly in the 60s, following overnight lows from the mid-40s to the lower 50s. Tonight’s lows should be about the same, with high readings Sunday in the mid-60s and low 70s.

Burback said there is still no prospect of any substantial rain in the near future, although there could be a few light showers again by next Wednesday or Thursday.

Times staff writer Eric Malnic and correspondent James Gomez contributed to this report.