Palm trees bend in the wind as a helicopter flies over homes threatened by the wind-driven Palisades fire in Pacific Palisades, California, on Tuesday.

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Red flag warnings have been extended through Friday for parts of Los Angeles and Ventura counties as gusty winds lash the area and several fires burn out of control.

A red flag warning means the combination of warm temperatures, low humidity and strong winds is expected to increase the risk of fire.

“Critical fire weather will continue through Friday in portions of LA and Ventura counties, including large wildfire areas such as the Palisades Fire, Eaton Fire and Hurst Fire,” the NWS says. “Gusty winds and very dry conditions will continue to result in fire outbreaks and existing fires. Please use extreme caution around ignition sources, pay attention to the weather forecast and follow instructions from local authorities.”

Another round of northeasterly winds is expected to develop Thursday, with winds strengthening and “another moderate to locally strong wind event forecast in Santa Ana,” the agency says. Widespread wind gusts will occur at speeds of 35 to 55 mph before increasing to 10 to 15 mph overnight into Friday morning. In combination with extremely low humidity, this promotes the formation of flames.

Winds have gradually subsided since the fires began, reaching speeds of up to 100 miles per hour in places.

The Santa Ana winds — dry, gusty winds blowing toward the coast — have fueled fires in Southern California this week. They are relatively common in the region, but meteorologists say the strength of the current is unusual.

“The typical strengths of the winds are on the order of, say, 30 to 60 miles per hour when they occur a few times a year,” Ariel Cohen, chief meteorologist for the NWS Los Angeles/Oxnard office, told NPR Morning edition. “Every now and then we get a much stronger wind event in Santa Ana like we have experienced over the last 24 to 36 hours. In this case, a widespread, life-threatening and destructive storm occurred.”

A wind advisory remains in effect until at least 2 p.m. PT on Friday. The NWS advises people in the area to stay at least 100 feet away from downed power lines and to call 911.

The California Newsroom tracks extreme weather across the region. Click through Reporting by LAist for the latest.

NPR’s Rachel Treisman and Ayana Archie contributed to this report.