upper waypoint

Bay Area Weather: Rain Likely to Return Friday, Along With Sierra Snow

Save ArticleSave Article
Failed to save article

Please try again

A person walks their dog in the rain on Haight Street in San Francisco on Nov. 22, 2024. After a very dry January, rain is expected to return to the Bay Area starting Friday. (Beth LaBerge/KQED)

For Bay Area residents who resolved to have a dry January: mission accomplished.

With no rain expected until at least Friday — the last day of the month — this January will go down as one of the driest on record in much of the region.

Take downtown San Francisco, which has gotten less than .2 inches of rain since the start of the year, an iota of the city’s 4.5-inch January average.

“Usually, we see probably half our water year within the January month,” said Brayden Murdock, a meteorologist at the National Weather Service’s Bay Area office. “So the fact that it’s that low is typically not great.”

But at least a bit of moisture is likely on the way, just in time for the weekend.

Sponsored

The persistent high-pressure ridge, which has parked itself over the West Coast, blocking storms for most of the month — and recalling the ‘ridiculously resilient ridge’ of 2013 — is expected to finally break down later this week, opening the door to wetter weather.

A low-pressure system spinning southward down the West Coast from Canada is expected to form a weak atmospheric river which could bring a moderate amount of rain to the Bay Area beginning Friday morning and continuing through the weekend, and possibly into Monday, Murdock said. So far, the North Bay is more likely to see heavier precipitation.

“The highest coastal mountains in northern Sonoma County will probably get close to 2.5 inches. And then as you go further south, much less,” he said, with about 1.25 inches expected to fall in Santa Rosa, half to three-quarters of an inch in San Francisco and the East Bay, and less than a quarter of an inch in San José.

After a bit of a pause, another system is likely to bring more rain to the area next Wednesday, he said.

“So it’s not going to make up the deficit that we saw, with as dry as January has been,” he said. “But at least this puts us in a step forward to seeing some of that rain come back into the forecast.”

As gray skies return to the region in the coming days, “it’s going to feel like winter again,” Murdock said.

The subtropical moisture the upcoming system will likely tap is also expected to lift this week’s frigid nighttime temperatures that have led to ongoing frost advisories and freeze watches and could bring some fresh snow to parts of the northern Sierra, including the Tahoe region for the first time in weeks.

Such a dry start to the year, in what is often the wettest month, may come as a shock after the last two Januaries, when massive atmospheric rivers drenched the Bay Area, dumping nearly 8.9 inches in 2023 and 6.6 in 2024, Murdock said. But the lack of rain is certainly not unprecedented.

“Back in 2015, we actually didn’t receive any rain in San Francisco. And then in 2014, we had .06 [inches],” he said. “So this isn’t the driest of the dry, but it’s still fairly dry, especially compared to the more recent years.”

That said, Murdock added, the longer-term forecast shows stronger chances of rain into February.

“It’ll be hard to kind of make up for that deficit, but it’s still a possibility.”

Despite the abnormally dry January, most of California’s major reservoirs still remain at above-average levels for this time of year after recovering significantly over the last two winters, according to data from the California Department of Water Resources (DWR).

But maintaining that supply through the year is contingent on significantly more rain and snowfall this winter, state officials say.

lower waypoint
next waypoint