Dangerous heat will intensify across Southern California Tuesday as temperatures climb toward their highest levels of the year and forecasters warn that widespread triple-digit heat will grip much of the region through Thursday.
An extreme heat warning will take effect at 10 a.m. Tuesday for much of Los Angeles County and remain in place through 8 p.m. Thursday, according to the National Weather Service.
The warning covers the valleys, mountains and inland portions of the coastal plain, where temperatures are expected to range from the 90s to as high as 110 degrees during the peak of the heat event Wednesday and Thursday.
A heat advisory will remain in effect through Thursday evening for coastal areas, including Los Angeles County beaches and the Palos Verdes Hills, where temperatures could still climb well into the 80s and 90s, forecasters said.
An extreme heat warning will also be in place for inland Orange County areas from 10 a.m. Wednesday to 8 p.m. Thursday, with a heat advisory in place during the same time frame for Orange County coastal areas.
“Big temperature rises expected to begin Tuesday, then peaking Wednesday with valley temps 100-110 and mid 90s across the interior portions of the coastal plain,” the weather service said.
Forecasters warned that lingering monsoonal moisture will boost humidity levels and make conditions feel even more uncomfortable.
“With the monsoonal moisture boosting humidity, widespread Major HeatRisk is expected Wednesday,” according to the NWS.
Overnight temperatures will offer little relief, with lows Tuesday night and Wednesday night expected to remain in the lower 70s in many communities, increasing the risk of heat-related illness.
A few showers and isolated thunderstorms will remain possible Tuesday afternoon and evening in the mountains of Los Angeles County.
Temperatures are expected to gradually ease heading into the weekend as onshore flow strengthens and cloud cover increases, although conditions are expected to remain above normal through at least Friday, forecasters said.
Authorities urged residents to drink plenty of water, limit outdoor activities during the hottest parts of the day, seek air-conditioned shelter when possible and check on elderly relatives, neighbors and others vulnerable to heat illness.