RELIEF FROM SANTA ANA WEATHER CONDITIONS EXPECTED FOR TODAY.

Byline: Sherry Joe Crosby Staff Writer

Santa Ana-like weather conditions continued for a second day Thursday with high temperatures, but calmer winds and more humidity reduced the risk of brush fires in the Los Angeles basin.

``It's the beginning of a cooling trend,'' said Joe Sirard, meteorologist for the National Weather Service. ``The onshore flow of air will return and gradually cool things down.''

Thursday's high at the Los Angeles Civic Center was 100 degrees. Woodland Hills baked at 104, Chatsworth hit 103 and Burbank reached 100.

Although no records were set in the San Fernando Valley, Los Angeles International Airport tied a 1965 record of 87 degrees and UCLA, toasty at 98 degrees, beat a previous record of 93 degrees set in 1945.

``It's a hot spell,'' Sirard said.

The warm weather is being caused by winds from the desert, which pass over mountains and grow warmer as they reach the basin.

``That's why it's felt hot and dry,'' Sirard said. ``It's basically high pressure over the Great Basin and air flowing out of the high (pressure system) from a northeasterly direction and that has pushed the marine layer from the coast.''

Southlanders can expect a respite from the heat starting today when temperatures are expected to return to the upper 70s along the beaches and in the Valley to the mid-80s on Saturday.

``The beaches will get a return of the sea breezes. They'll be back to where they were before,'' said Stuart Seto, a weather specialist for the National Weather Service.

Firefighters enjoyed a brief respite Thursday as calm winds and higher humidity levels reduced the risk of brush fires in the Los Angeles basin.

``If we see an upswing in the wind or a drop in the humidity, we can instantly pre-deploy our resources,'' said Brian Humphrey, spokesman for the Los Angeles City Fire Department.

On Wednesday, a red-flag warning prompted Los Angeles city and county firefighters to send additional fire engines and crews to high-risk brush fire areas throughout the San Fernando Valley.

The warning, lifted Thursday afternoon, was issued because gusting winds, low humidity and dry, volatile vegetation constituted the perfect ingredients for a brush fire, Los Angeles Fire Capt. Steve Valenzuela said.

``Yesterday the fire danger was extreme; today we're looking at high fire danger,'' Valenzuela said.

The only drawback to the cooler weather will be the return of smog, Seto said.

As the sea breeze comes in to the beaches and the Valley on today, Seto said, smog will return on Saturday.

But air quality experts don't expect the returning smog to ruin what is so far the cleanest year on record for Los Angeles.

Ten months into 1999, Los Angeles has not had a single smog alert - the result of the La Nina weather phenomenon and strict anti-pollution efforts.

``This year, barring a near meteorologic catastrophe, we'll be zero,'' said Sam Atwood, spokesman for the South Coast Air Quality Management District.

``It's the first time ever we've not had a Stage 1 ozone episode and we're even seeing many other areas of the country that have had higher peak ozone levels than we've had here.''

Atwood attributed the clean air to strict state and federal anti-pollution laws and the La Nina weather phenomenon, in which cooler than normal water in the eastern equatorial Pacific Ocean brings dry weather to Southern California. ``Everything from cleaner cars to cleaner businesses to cleaner consumer products'' has helped clear the air, Atwood said.

``In terms of the weather, it's been notable,'' Atwood said. ``We've not had a major episode of stagnation in the atmosphere the whole summer.''