Still Air, Fog Hold L.A.’s Smog in County : Condition Likely to Last Through Saturday; Cooler Days Ahead

There won’t be much frost on Orange County pumpkins this weekend, but there may be some unhealthy residue from the smog-laden, early morning fog in north and central areas of the county, as well as the Saddleback Valley, according to the South Coast Air Quality Management District.

“Most of the (smog) activity Thursday was in Los Angeles and spilled over into Orange County,” said the AQMD’s Armando Zumaya. “All the junk thrown in the air just sits there and collects in the fog.”

Zumaya explained that extremely weak winds in Orange County coastal areas allow impurities from the Los Angeles basin, especially ozone, to hang in the air until the sun burns off the fog. “The slightest bit of air movement will displace all these pockets,” he added.

Unfortunately for joggers and other early morning activists, the National Weather Service predicts continued morning fog and negligible winds for Orange County beach areas through Saturday, with generally fair weather and hazy sunshine during the day.

Highs today are expected to range from about 70 at the beaches to 80 in inland areas, dropping to 68 on the coast and 76 inland Saturday. Evening lows will be in the 50s, the weather service said.

Elsewhere, the Southland should have fine early fall weather this weekend, thanks to a high-pressure center off the Central California coast that is keeping Pacific storms safely to the north.

Fair skies and slightly warmer temperatures are expected today, according to the weather service. But the high-pressure center will weaken gradually, producing a gradual shift to an onshore flow of air. That should produce some coastal clouds at night and a slight cooling trend during the weekend.

It will be generally clear in Los Angeles, except for a bit of fog and low clouds along the coast in the morning hours. Highs will be in the low 80s, with overnight lows in the middle to high 50s.

Beachgoers will get a fair amount of sun once the morning clouds burn off, and the surf will run two to three feet at 10-second intervals. Mountain areas will see fair skies with slightly cooler days, as well as highs in the low to mid-60s and lows in the upper 30s and low 40s. Desert resorts should get plenty of sun, maximum temperatures in the high 80s and lows in the 50s.

San Diego will have sunny days with high temperatures in the mid-70s and lows in the 60s.

Elsewhere, San Francisco will experience foggy mornings and clear afternoons, with highs in the low 70s and lows dropping into the 50s. Las Vegas will be sunny over the weekend with highs in the upper 80s and lows around 50.