A sweltering heat wave will broil Southern California this weekend and early next week, prompting heat alerts and excessive-heat watches for some areas, according to the National Weather Service.
"It will be very hot," said Joe Sirard, a meteorologist with the service. "People should limit their time outside during the day."
So how hot will it get? Temperatures in downtown Los Angeles are expected to climb from the mid-80s Saturday to the mid-90s by Sunday, while triple-digit temperatures are on tap for the valleys.
But it's Monday, the first day of summer, that is expected to be hottest. The looming heat has prompted the National Weather Service to issue excessive-heat watches for L.A., the valleys and mountains Monday.
Dangerous, heat-related illnesses such as heat stroke are possible, the weather service said, especially among those who plan on spending Monday outdoors or people without access to air conditioning.
Forecasters warned against leaving people or pets in enclosed vehicles – even for a short period of time.
Power outages are possible as well, the weather service said.
Other agencies have also issued warnings against the heat. The Occupational Safety and Health Administration recommended frequent rest and breaks in shaded or air conditioned areas.
The Los Angeles County Public Health Department said it plans to issue a heat alert Sunday through Tuesday, when temperatures are expected to start to decline.
The dry and warm conditions come as firefighters continue to battle a massive fire in Los Padres National Forest, just north of Santa Barbara. The blaze forced the temporary closure of 30 miles of Highway 101 on Thursday night.
The blistering heat is the result of an upper-level ridge of high pressure that is building slowly over Southern California. Sirard said the system should start to weaken by Tuesday and temperatures should start to drop.
Despite the hot weather, Sirard said he doesn't expect any records to be broken, except possibly in the valleys.
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12:30 p.m.: This article has been updated with details about how to deal with the heat.