Stormy weather in the forecast Saturday through Christmas week

A FedEx worker pushes a cart stacked with packages on December 02, 2019 in San Francisco, California. A FedEx worker pushes a cart stacked with packages on December 02, 2019 in San Francisco, California. Photo: Justin Sullivan/Getty Images Photo: Justin Sullivan/Getty Images Image 1 of / 24 Caption Close Stormy weather in the forecast Saturday through Christmas week 1 / 24 Back to Gallery

If Santa brings you a croquet set, next week isn't going to be the time to use it.

Cool and showery weather is in the forecast Saturday night through Christmas week with a series of storm systems set to soak the San Francisco Bay Area.

The first storm arrives Saturday night and continues into Sunday, delivering mostly light to moderate rain mixed with brief, heavy downpours. The precipitation will begin in the North Bay and gradually spread southward into the central Bay Area.

"It looks like the system has slowed down a little," says Cindy Palmer, a forecaster with the National Weather Service. "It may affect the North Bay Saturday night, but it looks like it won’t arrive in San Francisco until until 8 p.m. or maybe even not until midnight. It looks like the heaviest rain will be Sunday morning and then lingering showers through the evening."

The storm will blast the region with chilly air and temperatures will begin to drop Saturday, pushing overnight lows into the 30s and 40s Christmas week. Gusty winds are possible, especially ahead of the storm on Saturday afternoon.

Projected rainfall totals with this storm are 1 to 2 inches in coastal hills and .5 to 1 inch elsewhere. Rain-sheltered inland valleys, such as the San Jose area, may see as little as .25 inch.

The system is expected to carry a cold and unstable air mass into the region and a chance of showers will continue into Monday.

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What comes next is uncertain. Monday night into Tuesday could see a break from the rain with a high-pressure ridge building and blocking storm activity. But some models show a trough of low pressure sweeping the region and delivering widespread rain late Christmas Eve into Christmas Day.

"The models are trying to take the system farther south," says Palmer. "Two of them still show the rain falling from San Francisco southward. I think most areas will get some light rain on Christmas but it may only be San Francisco southward with Monterey getting the brunt of it."

Earlier in the week, there was some speculation that Bay Area mountaintops may get a dusting of snow on Christmas. Palmer says now it's looking unlikely that Mount Diablo or Mount St. Helena will receive snow, but elevations above 4,500 feet in the Santa Lucia Range along the Big Sur coast could see some.

Yet another system is slated to hit Northern California Thursday, bringing light rain and gusty winds to the Bay Area Thursday afternoon and night.

"It’s really going to impact more interior areas like the Central Valley and the Sierra," says Palmer. "The Bay Area will get a few light showers and drizzle."

Temperatures will be unseasonably cool over the next week. "Daytime temperatures are going to be in the low- to mid-50s most of the week for most areas. Overnight temperatures are going to be on the cool side, low- to mid-40s and some interior-valley spots might dip into the 30s."

Amy Graff is a digital editor with SFGATE. Email her at agraff@sfgate.com.