The region's intense heat wave continues Wednesday as a strong ridge of high pressure remains parked over the southwest, once again making for triple-digit temperatures and poor air quality across the county.
Forecasters warned of the added risk of a fire weather watch for Thursday morning through Thursday evening. Recently, winds have been relatively light, so onshore winds are expected to increase later in the week. The flow, combined with high heat, low humidity and dry vegetation, could create a risk of extreme fire behavior.
An excessive heat warning will remain in force until 9 p.m. Wednesday in the San Gabriels, where temperatures of between 100 and 105 are expected, and in the Antelope Valley, where highs are expected to range between 106 and 110 through Friday.
A less serious heat advisory will be in force until 9 p.m. Wednesday in the Santa Monica Mountains Recreational Area and the Santa Clarita, San Fernando and San Gabriel valleys. The advisory, issued Wednesday, was allowed to expire in Los Angeles proper and beach cities.
Adding to the concern is the poor air quality. County health officials warned that air quality will be unhealthy for sensitive people in the San Gabriel and Santa Clarita valleys throughout the day. Health officials urged people with heart disease, asthma or other respiratory conditions to minimize outdoor activity. Schools were also urged to limit outdoor activity for children with sensitive health conditions.
The hot weather will increase the risk of heat-related illness and anyone working or spending time outdoors would be more susceptible, as will the elderly, children and those unaccustomed to the heat. Forecasters advised residents to reschedule strenuous activities to early morning or evening, drink plenty of water, wear lightweight and loose fitting clothing and be aware of the signs and symptoms of heat exhaustion and heat stroke.
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Authorities also warned against leaving children, seniors or pets in parked cars, which can heat up to lethal levels in just minutes, even with a window partially open.
The California Independent System Operator, which manages the statewide power grid, again issued a Flex Alert for Wednesday. It will will take effect at 2 p.m. and remain in force until 9 p.m., just like on Tuesday.
A Flex Alert is issued when the electrical grid is "under stress,'' generally from increased power usage due to hot weather. As part of the alert, residents were urged to make an extra effort to conserve during late afternoon hours, when air conditioners tend to be used most.
According to Cal-ISO's website, electrical demand late Tuesday afternoon topped 44,000 megawatts. The highest demand ever recorded by the system was 50,270 megawatts, which occurred on July 24, 2006.
Temperatures will remain high over the next several days, with small dips expected later in the week.