Southland's heat wave enters fourth day

The Southland's second heat wave of the summer will persist for a fourth day Thursday when several L.A. County communities will suffer triple-digit temperatures.

But no heat advisories are in effect anywhere in L.A. County.

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.

Related: Southland heat wave enters day three

Forecasters urged the public to drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, check up on relatives and neighbors,and never leave people or pets in hot cars.

The NWS said there's a 20 percent chance of showers and thunderstorms Thursday morning in Los Angeles, the San Gabriel, San Fernando and Antelope valleys, Santa Catalina Island, the Santa Monica Mountains Recreational Area and both coastal and inland Orange County. There's also a "slight'' chance of showers and thunderstorms in the San Gabriel Mountains.

The NWS forecast mostly cloudy skies today and highs of 79 degrees in Avalon and at LAX; 83 on Mount Wilson; 89 in Downtown L.A.; 91 in Long Beach; 94 in San Gabriel and Burbank; 95 in Pasadena; 100 in Palmdale and Saugus; 101 in Woodland Hills; and 102 in Lancaster. Temperatures will be slightly lower Friday under a combination of sunny and partly cloudy skies.

Partly cloudy skies were forecast in Orange County today, along with highs of 76 in San Clemente and Laguna Hills; 77 in Newport Beach and on Santiago Peak; 85 on Ortega Highway at 2,600 feet; 87 in Fremont Canyon; 88 in Mission Viejo; 89 in Fullerton, Irvine and Trabuco Canyon; and 91 in Yorba Linda and Anaheim. Friday's highs under sunny skies will be slightly lower.

CNS contributed to this report.