As many as three storms will roll in from the Pacific Ocean and bring rounds of soaking rain and high-country snow to California from late this week into early next week.
The first storm will roll ashore Thursday night, followed by a second storm Saturday night and Sunday, then a third storm on Tuesday.
The bulk of the rain will target central and northern areas of the state, according to AccuWeather Senior Meteorologist Ken Clark.
Hurricane Seymour, churning in the East Pacific, may also enhance storm impacts.
"However, some sporadic rainfall, even in the absence of Seymour is likely to reach Southern California, including the desert locations, as the pattern progresses," Clark said. "Some rain will also reach parched areas of Nevada, Arizona, Utah and Oregon."
While the rainfall from each storm will neither be huge nor break the back of the drought, cumulative moisture will ease wildfire concerns and put some runoff into streams and reservoirs.
"This series of storms can be very beneficial as main reservoirs are in the northern half of the state," Clark said.
Through Tuesday, rainfall will range from under 0.25 of an inch in the Mojave Desert to perhaps more than 8 inches in the Coastal Ranges and Sierra Nevada in the northern part of California.
Along with the benefits from the storms will come problems as well. The most far-reaching will be to hinder outdoor activities and cause travel delays.
The combination of water and buildup of oil on paved surfaces can make for extra slick conditions. Motorists should slow down on ramps and corners and allow extra stopping distance at intersections.
Where the rain falls at a fast pace, and the vehicles are traveling at high speed, the buildup of water can raise the risk of hydroplaning.
Mudslides can occur where heavy rain falls on the mountainsides and canyon walls. The greatest risk for flooding will exist in recent burn areas.
Flash flooding is possible along the normally dry streams and drainage basins in the southern part of the state with small stream flooding possible in central and northern areas.
Minor street flooding is possible during episodes of heavy rain including in San Francisco, Sacramento and Santa Barbara.
Rain and wind from Seymour will rapidly diminish well southwest of California by this weekend. However, leftover moisture from Seymour can be drawn northeastward and potentially could enhance downpours in Southern California, Arizona and southern Nevada as the non-tropical storm system spreads inland later this weekend.
In addition to rainfall, heavy snow is in store during part of the period over the high country in the Sierra Nevada, where a foot or two of snow can fall over the peaks and ridges.
Snow levels can dip down to Interstate 80 at Donner Pass, California, later Sunday night into Monday. A few inches of snow and slippery travel can occur over the pass.
Swells generated by Seymour, once a Category 4 hurricane with 150 mph, will reach the coast of Southern California in the form of large waves this weekend. The large swells could pose danger for surfers, bathers and boaters.
In the long term, rainfall is likely to be infrequent in Southern California this winter.
The first part of the winter holds the best chance of more rain and mountain snow events for northern areas, prior to expanding warm and dry conditions as the winter progresses, according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.