Rain in San Francisco, March 31, 2026.

The Bay Area is forecast to see scattered showers and even thunderstorms as back-to-back weather systems move into the area starting Thursday, according to the National Weather Service.

Weather service meteorologist Dylan Flynn said a low-pressure system is expected to arrive in the North Bay first, resulting in showers and a 20% chance of thunderstorms. He said this type of system, called a cut-off low, is separate from the jet stream, which can make it less predictable.

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Through Thursday evening, the rest of the Bay Area, including San Francisco, sees an increasing likelihood of scattered showers.

On Friday, the stormy weather is likely to pick up, and San Francisco is forecast to have a 90% chance of rain.

The heaviest and stormiest of days is likely to be Saturday, when the previous low-pressure system meets the jet stream, Flynn said.

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“Come Saturday, the jet stream takes a big dip, and a big trough comes down and picks up that low,” Flynn told SFGATE. “And where those two things combine, we have moisture from the cut-off low, and then we start to get some upper-level winds from the jet stream. And that just makes a more active shower and thunderstorm environment.” 

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Flynn said the entire Bay Area could see at least an inch of rain through Saturday, with coastal ranges potentially seeing up to a few inches. There is also about a 20% to 30% chance of thunderstorms on Saturday. While the rain is likely to be beneficial, Flynn cautioned occasional heavy showers could lead to hazardous roadways.

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“If you have a 30-minute shower that’s producing a high rain rate, that can cause localized flooding, especially across urban areas,” he said. “… If the storm drains are clogged or anything like that, it can lead to some ponding on the roadways.”

On Sunday, the wet weather should taper off, as a high-pressure system is expected to arrive, according to the weather service’s forecast discussion.

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The storm systems are expected to also bring much-needed snow to the Sierra Nevada. The National Weather Service in Reno has issued a winter storm watch for the eastern Sierra Nevada and Tahoe Basin. About 12 to 28 inches of snow is expected on the Sierra Crest, with 6 to 10 inches at lake level.

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