ORANGE COUNTY, CA — Rain, snow and unusually cold temperatures are in the forecast for Southern California this week, setting the stage for a soggy Thanksgiving and presenting a challenge for those planning to drive or fly for the holiday weekend. The National Weather Service warned of the major storm expected to hit the area Wednesday, Thursday and Friday.

"Though exact timing remains uncertain, confidence is high that widespread rain, heavy at times, will affect the region for the holidays," the NWS said. Although the rain isn't expected to arrive until Wednesday, expected tidal overflow has prompted officials to issue a coastal flood advisory in the Southland until 10 a.m. Tuesday.

Strong winds and slightly cooler temperatures are expected Monday. A high wind warning is in effect from noon to 3 a.m. Tuesday for northwest winds across the mountains and the Antelope Valley. Gusts could get as high as 60 mph, according to the NWS. Cloudy skies are forecast in Orange County, along with highs ranging from 53 on Santiago Peak; 60 on Ortega Highway at 2,600 feet; 65 in Laguna Beach and San Clemente; 66 in Fremont Canyon and Newport Beach; 68 in Yorba Linda and Mission Viejo; 69 in Fullerton; 70 in Anaheim; and 71 in Irvine. Tuesday will seen increased clouds will build in advance of the storm. Forecasters say rain will hit the area overnight, bringing heavy precipitation Wednesday and Thursday.

One to two inches of rain are expected along the coast and valleys and up to three inches in the mountains and foothills. The rain threatens to wreak havoc on one of the busiest travel weekends of the year. More than 4.3 million Southland residents plan to travel 50 miles or more away from home this Thanksgiving, according to the Automobile Club of Southern California.

That would be the highest Thanksgiving volume on record for California travel and the second-highest travel volume nationally since AAA began tracking in 2000, trailing only the record set in 2005.

Of the 4.3 million Southern Californians expected to take Thanksgiving trips, 3.7 million will travel by car, 500,000 by aircraft and 123,800 will rely on other modes of travel, including buses and cruise ships.

The NWS Monday morning issued a winter storm watch for the San Gabriel Mountains from late Tuesday night through late Thursday night. During that time, "travel could be very difficult to impossible. The hazardous conditions could result in temporary road closures, including on Interstate 5 through the Grapevine. Gusty winds could bring down tree branches," according to an NWS statement. The NWS said there was the potential for road closures later in the week due to possible snow and ice on the I-5 Grapevine.