The National Weather Service has issued an excessive heat watch for Southern California from Tuesday through Thursday, warning that temperatures will jump sharply just as the region moves into the first full week of summer. Downtown Los Angeles and the L.A. metro area are forecast to reach 90 degrees, while some valleys could push well past that.
The alert comes after the last day of spring brought only a 75-degree high on Saturday. By Wednesday, the hottest day is expected, highs in the San Gabriel Valley and the San Fernando Valley could reach the mid-90s, and the Antelope Valley and the Cuyama Valley in Santa Barbara County could climb to 100 degrees or higher.
That is the sort of heat that changes how a day feels before noon. Carol Ciliberti said the system is driven by “a really strong ridge of high pressure” centered over Arizona and New Mexico and their southern border with Mexico, and that it expands west into Southern California. She warned that the hotter air raises the risk of heat-related illness, especially for the young, the elderly and people without air conditioning, and added: “Do not take your dogs hiking — please.”
The weather shift carries a mixed edge. The heat wave should finally bring some relief from June Gloom, but it also raises fire danger as fuels dry out and tall fire plume potential grows over the valleys and mountains. That matters because the region is already dealing with smoke and bad air from a stubborn warehouse fire in Boyle Heights, and officials on Saturday extended a health advisory until 12:30 p.m. Sunday. Air quality is expected to range from unhealthy for sensitive groups to very unhealthy in central Los Angeles County, the San Gabriel Valley, the east San Fernando Valley and the northwest San Bernardino Valley, with conditions possibly worsening overnight if winds ease.
If the wind shifts Sunday morning, smoke could move toward southeast L.A. County, and high humidity may create visibility problems overnight. Ash could also fall in the area. To give people a place to get out of the smoke, the city of Los Angeles opened a smoke respite shelter at Pecan Recreation Center at 145 S. Pecan St., and the county opened another at City Terrace Park at 1126 N. Hazard Ave.
The one unresolved question is how long the heat will linger after Thursday. For now, the watch is a clear warning that Southern California is headed from a mild spring into several days of punishing heat, with Wednesday set to be the peak.
