Parts of the Southland were expected to see slight relief Sunday from the worst heat wave in years, before temperatures rise again to dangerous levels beginning Tuesday.
A heat advisory was in effect until 9 p.m. Sunday for the greater Los Angeles area, but the high in downtown Los Angeles was expected to be between 88 and 90 degrees — an improvement from Saturday’s high of 99.
Excessive heat warnings remained in effect through 9 p.m. Wednesday in the Antelope, Santa Clarita and San Fernando valleys, where more triple-digit temperatures were expected Sunday. A high of 108 was expected in Lancaster, 104 in Palmdale, and 100 in Woodland Hills and Santa Clarita.
“Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities,” warned a National Weather Service statement.
“Take extra precautions if you work or spend time outside,” it urged. “When possible, reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose-fitting clothing when possible.”
The NWS noted that the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments for people performing outdoor work.
Cooling centers opened in the city and county of Los Angeles to give residents a place to escape the heat. Due to COVID-19 social distancing requirements, capacity is limited and people are should call ahead to check space availability, according to the Los Angeles Department of Recreation and Parks. Information on the county’s cooling centers as well as heat-related illnesses and prevention is at publichealth.lacounty.gov.
The heat was making life tough for firefighters battling two wildfires in Los Angeles County. The Lake Fire in the Lake Hughes area had burned 17,862 acres and was 12% contained Saturday afternoon, while the Ranch 2 Fire in Azusa had burned 2,256 acres and was 7% contained.
The NWS warned of elevated critical fire-weather through Monday, in part because of very dry vegetation, providing fuel for wildfires. Another factor is the fact that surface winds coming from the north will be weak, keeping the ground warm. But no red flag warnings have been issued.
Unhealthy air quality was expected Sunday in the San Gabriel Valley and the San Gabriel Mountains, the Santa Clarita Valley, the west San Fernando Valley and the Pomona-Walnut Valley.
The California Independent System Operator, which runs the state’s power grid, called for voluntary electricity conservation. Residents and businesses were being asked to reduce their energy consumption, especially between the hours of 3 and 10 p.m.
CAL-ISO initiated some rolling blackouts Friday and Saturday for the first time since 2001.
Forecasters also warned of a chance of thunderstorms in the mountains late Sunday morning, and a flash flood watch was in effect through Sunday evening for the Antelope Valley and the L.A. County mountains excluding the Santa Monica range.
Tuesday was expected to be the worst day of the entire heat wave, with highs expected to reach 109 in Lancaster and Santa Clarita, 107 in Chatsworth and 103 in Pasadena. More dangerously high temps are forecast for Wednesday and Thursday, before the heat wave is finally expected to ease up on Friday.