First Day of Fall--Don’t Let the Coolness Fool You

Fall arrived in Southern California on Thursday like a beautiful stranger--warm but with a just a hint of coolness. Things won’t stay that way, forecasters warn. They never do.

“Something will change,” said meteorologist Dave Beusterien of WeatherData Inc., which provides forecasts for The Times. “This kind of weather does not last too long this time of year.”

For the next few days, however, Beusterien said, there will be “only minor variations.”

The weekend should be fair and a little warmer than Thursday’s Civic Center readings in the mid-70s, with temperatures returning to normal early next week as a branch of the jet stream shifts south to bring an increase in sea breezes along with more night cloudiness.

As fall officially clocked in at 12:29 p.m., Southlanders could look back on a summer that was relatively pleasant, except for a scorching heat wave over the Labor Day weekend, when the Civic Center high was a record-shattering 110 degrees.

Actually, Beusterien noted, that blast of hot air was not the result of a Santa Ana condition, which can be expected anytime now for a while. He said Southern California came close to getting one last week, “but another storm system came in, deepened the onshore flow and caused pressures to flow.”

The warmer-than-normal weather expected this weekend will be the result of a weak high-pressure system building in the upper atmosphere, said the forecaster, boosting temperatures 3 to 5 degrees along the coast and 5 to 7 degrees inland.

The National Weather Service said Thursday’s Civic Center high was 76 degrees after an overnight low of 56. Normal high for the date is 82. Relative humidity ranged from 78% to 42%.

Along Southland beaches, the surf is expected to be 2 to 3 feet today and Saturday from Santa Barbara to San Diego.