A record-breaking heat wave combined with gusty Santa Ana winds has created extreme fire conditions across parched wild lands in the Southland, forecasters warned.

Red flag warnings for Los Angeles and Ventura counties have been extended until 3 p.m. Friday with abysmally low humidity worsening already tinder-dry conditions. Wind gusts of up to 50 mph are possible in mountain areas, the National Weather Service said.

The circumstances are such that if a fire were to ignite, "there could be rapid spread of wildfire," the weather service warned Thursday.

The weather service said the unseasonably warm weather and Santa Ana winds were the result of high pressure near the surface of the Great Basin coupled with high pressure aloft just west of Southern California, blocking storm systems from reaching the region.

The combination is keeping temperatures 15 to 20 degrees above normal, tying or breaking records across the Southland.

On Wednesday, Point Mugu Naval Air Station, Fullerton and Camp Pendleton reached 90 degrees, tying for the day's highest temperature in the nation, according to the National Weather Service.

Downtown Los Angeles hit 85, tying a daily record set in 2009. Bob Hope Airport in Burbank recorded a high of 86, breaking by one degree a record for the day set in 1976.

Santa Barbara Airport also broke a daily record, topping out at 82 degrees.

Conditions were expected to remain largely unchanged for Thursday, with temperatures ranging from the 70s to the upper-80s in the coastal and valley areas, according to the weather service.

The ridge of high-pressure is so strong, that daytime temperatures in the 80s are expected to last through Monday in the Los Angeles region before starting to cool slightly on Tuesday.

"The high is so strong that nothing can really break it," said National Weather Service meteorologist Curt Kaplan.

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