Heat is on in Southern California

The sun shining over Pasadena Tuesday, July 13, 2010.
The sun shining over Pasadena Tuesday, July 13, 2010.
Mike Roe/KPCC

Parts of the Southland are going to swelter today, and triple-digit temperatures may combine with monsoonal humidity to reach dangerous heat thresholds.

Updated 7:38 a.m.

An excessive heat warning was issued this morning through Friday morning for the San Fernando and Santa Clarita Valleys, and for Los Angeles County mountains including the Santa Monica range. The warning was issued by the National Weather Service in Oxnard.

"Everywhere you go except the immediate beaches, it's going to be hot and more humid out there," Weather Service meteorologist Andrew Rorke said. "Avoid direct sun and drink plenty of water."

Los Angeles County is going to be hotter than Orange County, according to forecasts.

In downtown Los Angeles and Malibu, the high is expected around 93, about the same as Anaheim, according to the Weather Service. In Hollywood and Sierra Madre, the high will be about 97, Burbank and Pasadena can expect 102 or hotter, and the forecast high in Santa Clarita today is 106.

High pressure will continue to strengthen as it builds into southwestern California, according to a NWS advisory. Temperatures are expected to climb to over 100 degrees across interior sections of the forecast area, including lower mountain elevations and portions of Los Angeles county valleys.

During the peak of the heat wave, some monsoonal moisture may filter into the area today and persist through at least Friday.

"The combination of heat and added humidity will add to the discomfort level," the NWS advisory stated.

The Weather Service noted that in the Santa Clarita Valley, the combination of heat and humidity could make it feel more like 110 degrees.

The Los Angeles County Department of Public Health earlier this week issued a warning for residents of Lancaster and other parts of the Antelope Valley to take precautions as the heat wave settles in.

"While people don't need to be told it's hot outside, they do need to be reminded to take care of themselves, children, the elderly and pets when the weather gets hotter," Dr. Jonathan Fielding said. "When temperatures are high, prolonged sun exposure may cause dehydration, heat cramps, heat exhaustion and heat stroke."

Symptoms of dehydration and heat cramps include dizziness, fatigue, faintness, headaches, muscle cramps and increased thirst. Those with symptoms should be moved to a cooler, shaded area and given water or sports drinks.

More severe symptoms such as diminished judgment, disorientation, pale and clammy skin, a rapid and weak pulse or fast and shallow breathing may indicate heat exhaustion or impending heat stroke and may require immediate medical attention. Heat stroke may lead to brain damage and death.

"Never leave children, elderly people or pets unattended in closed vehicles, even with the windows `cracked,'" Fielding said, "because temperatures inside can quickly rise to life-threatening levels."

Tips for beating the heat include:

– wear light, loose-fitting clothing with long sleeves and a wide-brimmed hat;

– drink water or sports drinks often – don't wait until you are thirsty – and avoid drinking alcohol;

– during peak heat hours, stay in an air-conditioned area; if your home is not air-conditioned, visit public facilities such as shopping malls and libraries; and

– avoid unnecessary exertion outside during peak sun hours.

Fielding also urged residents to offer help to neighbors with limited access to air conditioning and transportation and check on them frequently.

Additional information and a list of cooling centers can be found at www.publichealth.lacounty.gov or on the L.A. County Information line at 2-1-1.

The scorching summer heat has been prompting spikes in electricity use, and the Department of Water and Power urged consumers to take steps to conserve power today to avoid straining on electric grid.

With temperatures expected to exceed 100 degrees in the San Fernando Valley, DWP officials said energy demand will likely peak at 5,600 megawatts, after hitting 5,270 megawatts Wednesday.

"Any time energy demand exceeds this level, we need to begin conserving wherever possible, while not jeopardizing anyone's health or safety,'' DWP Chief Operating Officer Raman Raj said.

"Saving power not only conserves energy but also reduces the possibility of strain on power system infrastructure,'' he added.

The DWP offered tips on reducing power consumption:

– Adjust the thermostat to 78 degrees;

– Limit the use of appliances such as washing machines, dishwashers and vacuum cleaners during the day, and use them at night instead;

– Try to avoid cooking during the day to avoid adding to the heat inside the home;

– Open windows and doors at night and early morning to improve ventilation;

– Close draperies, shades or blinds to block sunlight; and

– Turn off lights and equipment when not in use.

DWP customers interested in cooling off with a room air conditioner can avail of a $50 rebate on a qualifying EnergyStar-rated model. Those installing a central air conditioner can get a $100 rebate.

Customers who want to plant shade trees can receive up to seven shade trees for free under a separate program.

This story incorporates information from the Associated Press.