Southland heat wave enters day three

The Southland's second heat wave of the summer enters its third day Wednesday, with some of the week's highest temperatures expected in the valleys, and a heat advisory in place until 9 p.m. for the San Fernando and Santa Clarita valleys.

"The combination of very high temperatures and humidity creates a dangerous situation in which heat illnesses are possible,'' according to the National Weather Service. "Temperatures inside vehicles, even if the windows are partially open, can quickly rise to life-threatening levels.''

Forecasters urged the public to "drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.''

The National Weather Service said the heat wave, which is accompanied by monsoonal moisture out of Mexico, meaning it may feel even hotter than what the thermometer shows, will persist through the weekend. Forecasters warned that this week's weather brings the potential of heat-related illnesses, especially for the homeless, the elderly, infants, and anyone participating in outdoor activities.

Long Beach reached 96 degrees on Tuesday, breaking the record for that date of 94 degrees, set in 1974.

A number of communities hit triple digits, including Pasadena, Van Nuys, Chatsworth, Woodland Hills and Saugus.

The heat wave results from high pressure over the nation's Four Corners region, said NWS meteorologist Curt Kaplan. It has no meteorological connection to the hot weather on the East Coast.

Over the next few days, air circulating clockwise will pick up moisture from Mexico, including Baja California, Kaplan said. There's no expectation of flash flooding, he said, but there could be an elevated danger of fire amid the dryness at lower elevations if thunderstorms develop and generate lightning, including dry lightning.

There was a slight chance of afternoon thunderstorms Wednesday in the mountains and the Antelope Valley, according to an NWS statement.

A slight cooling trend will get underway toward week's end.

The NWS forecast partly cloudy skies in L-A County Wednesday and highs of 80 degrees at LAX; 82 on Mount Wilson; 84 in Avalon; 88 in Long Beach; 90 in downtown L.A.; 94 in San Gabriel; 96 in Burbank; 97 in Pasadena; 102 in Palmdale and Woodland Hills; 103 in Lancaster; and 104 in Saugus. Thursday's highs will be 3-4 degrees lower.

Sunny skies were forecast in Orange County along with highs of 76 in Newport Beach and San Clemente; 77 in Laguna Beach; 82 on Santiago Peak; 90 on Ortega Highway at 2,600 feet; 92 in Irvine; 93 in Fullerton in Mission Viejo; 94 in Fremont Canyon, Anaheim and Yorba Linda; and 95 in Trabuco Canyon. Thursday's temperatures will be a couple degrees lower.

CNS contributed to this report.