LAKE FOREST, CA — Lake Forest is trading rain for a hot and humid stretch this week after Tropical Storm Marie brought showers to Southern California over Labor Day weekend.
An extreme heat warning is in effect for inland Orange County through 8 p.m. Wednesday, with temperatures expected to climb into the 90s, according to the National Weather Service. A heat advisory will follow from Wednesday evening through Thursday.
The heat will come with unusually high humidity as moisture from Marie continues to stream across Southern California.
"The heat ... will be exacerbated by the increased humidity due to Marie moisture. So, today will feel quite uncomfortable across the area," forecasters said.
Extreme heat warnings remain in effect through Wednesday evening for much of Orange County, the Inland Empire and San Diego County, where highs could reach 108 degrees in some valleys, and 111 in the desert, according to the National Weather Service. Those warnings will transition to heat advisories Wednesday night and continue through Thursday.
The warmest temperatures are expected Wednesday in the Inland Empire and on Tuesday and Wednesday in Orange and San Diego counties.
The most dangerous heat is expected in the deserts, where temperatures could climb well above 110 degrees. An extreme heat warning is in effect through Friday evening for the Coachella Valley, San Diego County deserts and the San Gorgonio Pass, where highs of 106 to 110 degrees are expected.
| City | Tues. | Weds. | Thurs. |
|---|---|---|---|
| Banning | 96 | 101 | 99 |
| Laguna Beach | 84 | 85 | 80 |
| Lake Elsinore | 102 | 106 | 101 |
| Long Beach | 84 | 92 | 85 |
| Los Angeles | 95 | 98 | 92 |
| Malibu | 91 | 88 | 83 |
| Mission Viejo | 97 | 98 | 92 |
| Murrieta | 100 | 103 | 98 |
| Newport Beach | 85 | 86 | 81 |
| Northridge | 99 | 105 | 103 |
| Oceanside | 81 | 81 | 77 |
| Palm Desert | 106 | 109 | 110 |
| Redondo Beach | 80 | 82 | 84 |
| San Diego | 87 | 86 | 84 |
| Santa Ana | 95 | 96 | 91 |
| Santa Monica | 92 | 90 | 82 |
Heat advisories are in effect through Thursday for Los Angeles County beaches and coastal valleys and the Santa Monica Mountains. Forecasters said there is also a 20% to 30% chance that humidity will climb high enough Wednesday to warrant upgrading some areas to excessive heat warnings.
In the Los Angeles Basin, temperatures are expected to peak Wednesday between 91 and 100 degrees. Coastal communities will range from the mid-80s to around 90 at the beaches, while areas farther inland could reach the mid-90s.
The San Fernando Valley is expected to see highs of 98 to 106 degrees Wednesday, while the San Gabriel Valley will reach 96 to 100.
Some relief will arrive Thursday near the coast, but inland areas will remain hot. San Fernando Valley temperatures are expected to remain between 96 and 102 degrees Thursday.
Forecasters warned that unusually warm overnight temperatures will provide little relief — with lows across many coastal and valley areas remaining in the 70s — and significantly increase the risk of heat-related illness.
The abrupt heat follows a stormy holiday weekend in which Marie, while remaining well offshore, sent tropical moisture and large waves toward Southern California.
The storm generated "life-threatening" beach conditions, National Weather Service meteorologist Rose Schoenfeld said. Some south-facing beaches saw surf as high as 10 feet.
Newport Beach lifeguards carried out 177 rescues Saturday, lifeguard battalion chief Adam Yacenda said.
In Malibu, pounding surf caused a beachfront home's driveway to collapse into a large sinkhole Tuesday morning, rupturing a gas main.
Flooding was reported at numerous beaches. One TikTok video showed a large group of beachgoers pushing a seemingly stuck car out of floodwaters in Seal Beach over the weekend.
And in Long Beach, damage to a seawall during high surf conditions forced the evacuation of about 20 homes.
The unsettled weather is not entirely over. The NWS said isolated showers and thunderstorms remain possible through Tuesday around Los Angeles County, with brief periods of moderate to heavy rain possible.
In Orange, Riverside and San Diego counties, a slight chance of showers and thunderstorms will continue through Thursday, with the best chances over mountain areas during the afternoon.
Hazardous surf will also remain a concern into Tuesday as a significant southerly swell continues along the coast.
Cooling should begin spreading inland Thursday and Friday, according to forecasters.
Material from City News Service and the Associated Press was used in this report.
Sign up for free local newsletters and alerts for the
Lake Forest Patch
Patch.com is the nationwide leader in hyperlocal news.
Visit Patch.com to find your town today.