An excessive heat warning was extended for another day Sunday as parts of the Southland continue to bake under extreme heat during the long Fourth of July holiday weekend.
The warning is now in effect until 8 p.m. Monday in the Santa Clarita Valley, the Antelope Valley and the foothills, according to the National Weather Service, which warned of the potential for heat-related illnesses.
A less-severe heat advisory was in effect during the same hours in the western San Gabriel Mountains.
Lancaster and Palmdale reached 105 degrees Sunday, with Santa Clarita reaching 99 and Valencia 97, the weather service reported. Temperatures were in the mid-90s in the San Fernando Valley and the upper 80s in the San Gabriel Valley.
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The South Coast Air Quality Management District also issued an Ozone Advisory through Monday, warning that the excessive heat could increase the likelihood of poor air quality in many areas. Ozone exposure can be hazardous for children, older adults, and people with asthma or COPD. A map highlighting the air quality in various areas is available at aqmd.gov/aqimap.
The hot and dry conditions were also creating elevated wildfire risk.
“Drink plenty of fluids, stay out of the midday sun, and check up on relatives and neighbors,” the NWS advised. “Young children and pets should never be left unattended in vehicles under any circumstances.”
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The heat is the result of a building high-pressure system, which will bake inland areas. Beaches are expected to be popular destinations for the weekend, with forecasters noting that “a persistent marine layer and onshore flow” will keep temperatures down in coastal areas.
Forecasters noted that in the hottest areas, overnight temperatures won't offer much relief, falling only into the 70s to near-80 in some locations.
“While more sunshine will be prevalent and much warmer temperatures will develop away from the coast, the beaches will be mired in low clouds into the afternoon,” according to the NWS. “As a result, the warming trend will be moderated for the coastal areas.”
The high-pressure system is expected to dissipate beginning Monday, although temperatures should remain above normal for the Fourth of July holiday on Tuesday. More significant cooling is anticipated Wednesday and Thursday.
