A fire weather watch heralding the advent of critical fire weather will go into effect in LA and Orange counties beginning Sunday afternoon, lasting through early Monday evening, the National Weather Service said Saturday.
Strong Santa Ana winds combined with very dry vegetation could create extreme fire danger and fire behavior, the NWS said.
A new Santa Ana wind event is likely to develop late Sunday, producing winds of 20 to 35 miles per hour generating gusts of between 40 and 50 mph in Los Angeles and Ventura Counties, with isolated 60-mph gusts possible in the San Gabriel county mountains, amid humidity levels of only between 5 and 15 percent.
The strongest Santa Ana winds are expected late Sunday night into Monday morning, forecasters said.
"This may result in another period of critical fire weather conditions, which led to the issuance of a Fire Weather Watch for most of Los Angeles and Ventura counties," said an NWS statement.
The fire weather watch will be in effect in the San Gabriel and Santa Monica mountains, the Angeles National Forest, the Santa Clarita, San Fernando and San Gabriel valleys, the L.A. County coast, and metropolitan Los Angeles, including Downtown L.A.
A more serious red flag warning will be in effect from 10 p.m. Sunday until 6 p.m. Monday in Orange County, where winds of 15-25 miles are possible along with gusts of 35-50 mph, with peak gusts of 70 mph possible, according to the NWS.
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The wind will be light in Orange County on Tuesday and humidity levels will rise, but another moderate to strong Santa Event is possible by Wednesday, it said.
"If fire ignition occurs, conditions will be favorable for extreme fire behavior and very rapid growth, which would threaten life and property," according to the statement.
Also in force from late Sunday through Monday morning will be a freeze watch in the Antelope Valley, with temperatures dipping as low as 28 degrees, according to the NWS.
"Frost and freeze conditions could kill crops and other sensitive vegetation and possibly damage unprotected outdoor plumbing," warned an NWS statement.
"Take steps now to protect tender plants from the cold. To prevent freezing and possible bursting of outdoor water pipes, they should be wrapped, drained, or allowed to drip slowly. Those that have in-ground sprinkler systems should drain them and cover above-ground pipes to protect them from freezing."
The NWS forecast sunny skies in L.A. County Monday and temperature highs as low as 16 degrees cooler than today's, including 62 on Mount Wilson; 69 in Palmdale and Lancaster; 70 in Avalon and Saugus; 72 in Burbank and San Gabriel; 73 at LAX; and 74 in Long Beach, Downtown L.A., Pasadena and Woodland Hills.
Tuesday's highs will be lower in some communities on Monday but around four degrees higher in most.
A mix of sunny and partly cloudy skies is expected in Orange County Sunday, along with highs of 61 on Santiago Peak; 65 on Ortega Highway on Ortega Highway at 2,600 feet; 69 in Laguna Beach and San Clemente; 70 in Newport Beach; 73 in Trabuco Canyon; 74 in Fullerton and Mission Viejo; 75 in Yorba Linda and Freemont Canyon; and 76 in Anaheim and Irvine. Monday's temperatures in Orange County, still under sunny skies, will be about the same in some communities and a few degrees higher in others.