A rare variation of a high-wind warning has been issued for the northern San Fernando Valley and eastern Ventura County that could have ripple effects on the massive wildfires burning in Pacific Palisades and Altadena.

A “particularly dangerous situation” — an official level of alert — that could cause fires to spread rapidly may kick in about 4 a.m. today. It was expected to last until about noon Wednesday, the National Weather Service said.

“It’s a heightened state of alert” is how James Brotherton, a meteorologist for the weather service, described the special red-flag warning. “That’s basically very dry conditions in the air and very dry conditions on the ground combined with very strong winds. All three of those critical ingredients are at extreme levels.”

The winds, blowing from the northeast, are expected to be particularly strong in the western San Gabriel Mountains/5 Freeway corridor; the northern San Fernando Valley, mainly the 118 and 210 freeway corridors; the mountains in the Santa Susana Pass and Ventura County; and in the Ventura County valleys, mainly near Simi Valley, Moorpark and Santa Paula.

Wind gusts of 55 mph to 70 mph are possible. Such winds could spread embers well ahead of any fire.

The weather service issued similar warnings three times in the past three months, Gov. Gavin Newsom said in a social media post.

The first preceded the Mountain fire, which erupted Nov. 6, in Ventura County and destroyed 243 structures. The second was made in advance of the Franklin fire, which started Dec. 9 in Malibu and destroyed 20 structures. The third preceded the Palisades and Eaton fires, which both began Jan. 7 and have damaged or destroyed more than 12,000 structures.

The winds are not expected to be as fierce in the Palisades and Eaton fire areas, Brotherton said. Gusts there could reach 35 mph.

Elsewhere in Southern California, red-flag warnings are in effect through 6 p.m. Wednesday. The forecast calls for winds of 20 mph to 30 mph in much of those areas with gusts up to 55 mph.

Residents near wildland areas should be prepared to evacuate if a fire ignites. Information on creating an evacuation plan is available at readyforwildfire.org. Drivers should watch out for debris and smoke.

Aside from the winds, the weather in Southern California should be tame through Sunday, according to the forecast, with clear skies and temperatures reaching the high 60s in much of the region by Wednesday before decreasing to 60 by Sunday. The lows are forecast to be in the mid-40s, with the exception of the Riverside area, where a frost advisory with lows of 40 degrees was issued through this morning.

The San Bernardino Mountains will be chilly, with highs in Big Bear predicted to be in the 40s and lows in the teens through Sunday. Idyllwild in the San Jacinto Mountains will be warmer, with highs in the 50s and lows in the 30s.

In Wrightwood in coming days, the forecast calls for highs in the 40s and lows in the upper 20s to low 30s.