Atmospheric river meets king tides, flooding Bay Area roads as Sierra blizzard snarls travel

Floodwater lapped at the doors of stranded cars on Highway 101 in Marin County on Saturday as rescue crews maneuvered inflatable boats through what is normally one of the Bay Area’s busiest commuter routes. A hundred miles to the east, whiteout conditions on Interstate 80 over Donner Summit forced traffic to a standstill while wind gusts over 100 mph shut down ski lifts along the Sierra ridgeline.

Both scenes unfolded under the same storm: California’s first major atmospheric river of 2026, which slammed into the state just as some of the highest tides in decades surged into San Francisco Bay.

Over the first weekend of January, a moderate to strong atmospheric river—a narrow band of moisture often called a “river in the sky”—made landfall along the California coast and was forecast to linger through at least Monday. The timing coincided with so-called king tides, when the alignment of the sun, moon and Earth produces the largest tidal swings of the year.

The overlap turned a forecast coastal flood into one of the Bay Area’s most significant high-water events since the late 1990s and set up blizzard-like conditions in the Sierra Nevada, disrupting travel even as the storm began rebuilding the state’s vital mountain snowpack.

King tides push Bay water to decades-high levels

The National Weather Service office in Monterey issued a coastal flood warning for San Francisco Bay shorelines and low-lying North Bay valleys from Friday morning through early Saturday afternoon, citing the rare combination of astronomical tides and incoming storm surge.

“Significant coastal flooding [is] expected due to high astronomical tides and storm surge,” forecasters warned in a statement. “Up to 2.5 feet of inundation above ground level is possible in low-lying areas near shorelines and tidal waterways. Numerous roads will be closed. Low lying property including homes, businesses, and some critical infrastructure will be inundated.”

At the San Francisco tide gauge, water levels Friday morning climbed to about 7.2 feet, or roughly 2.2 feet above normal high tide. On Saturday morning the tide was expected to reach about 7.1 feet, about 2.5 feet above normal—a level forecasters said has not been observed there since 1998.

Preliminary observations at Crissy Field showed water about 2.56 feet above a reference level, which a weather service meteorologist described to local media as near-record for the Bay Area and among the highest readings since the strong El Niño winter of 1982–83.

Those numbers translated into dramatic scenes on the ground, particularly in Marin County, where low-lying areas have long been vulnerable during winter storms and king tides.

Marin County streets turn to waterways

From Sausalito to San Rafael, water poured out of creeks and across roads as the high tide peaked late Saturday morning. Sections of Highway 101 near Corte Madera briefly appeared to merge with San Francisco Bay, with traffic edging through standing water before authorities closed some on- and off-ramps.

Side streets fared worse. Lucky Drive, Doherty Drive and Fifer Avenue in Corte Madera and Larkspur, and Miller Avenue in Mill Valley, were among the corridors reported submerged. In some places water reached vehicle windows, forcing motorists to climb onto roofs or wait for help.

Along a roughly 15-mile stretch of shoreline, emergency crews carried out multiple rescues of people trapped in cars or on flooded roadways. Local fire departments and sheriff’s deputies used high-clearance vehicles and small boats to reach stranded drivers. No serious injuries were immediately reported in Marin, but officials said the situation could easily have turned deadly.

“The one thing that we want to emphasize is, if you see flooded roadways, do not try to drive through them,” one local official told television reporters at the scene. “You don’t know how deep the floodwaters are.”

In Larkspur, resident Mark Krawec said the water rose higher than he had seen in years.

“It’s never been this bad,” Krawec told a Bay Area TV station, describing three to four inches of water on his garage floor.

His house stayed dry, but he said neighbors were less fortunate as water pushed into driveways and low-lying first floors.

Businesses were hit as well. A gym in Corte Madera temporarily closed after floodwater entered the building. Parking lots around shopping centers in Corte Madera and Mill Valley filled like shallow lakes, with some customers wading through knee-deep water.

Across the bay in San Francisco, water sloshed over parts of the Embarcadero and into low-lying intersections. At Crissy Field, a popular waterfront park, the bay overtook trails and parking areas during the morning high tide, forcing visitors to retreat to higher ground.

In the East Bay, the California Highway Patrol shut down bus and carpool lanes near the Bay Bridge toll plaza after water pooled across the pavement. Officials urged commuters to avoid the area during the peak of the tide and use alternate routes.

Mudslides and heavy surf along the coast

The same storm system brought problems farther south. In Santa Barbara County, heavy rain triggered a mudslide along U.S. 101 near Goleta, sending debris onto the roadway and contributing to at least one death. Authorities said a man was swept into a creek during the downpour and later found dead.

Coastal flood advisories extended along much of the central and northern coastline from Sonoma to Monterey counties. While the open-ocean shoreline saw less deep standing water than the enclosed bay, forecasters warned of large surf, dangerous rip currents and beach erosion as the storm intensified.

Atmospheric river feeds Sierra snowstorm

Inland and at higher elevations, the moisture-laden storm took a different form.

National Weather Service offices in Sacramento and Reno issued winter storm warnings for much of the Sierra Nevada and the Lake Tahoe basin from late Friday through Monday morning. Forecasters said the storm would deliver 1 to 3 feet of snow at lake level and 3 to 5 feet or more above about 6,000 feet, with the heaviest totals expected along the crest.

Southwest winds over the ridge tops were forecast to exceed 100 mph, and some resort sensors reported gusts as high as 128 mph on Saturday, forcing widespread lift closures at Palisades Tahoe and other ski areas.

Travel over the major passes deteriorated quickly. On Interstate 80, chain controls were in effect for long stretches between Colfax and Truckee, with Caltrans periodically holding traffic at chain checkpoints or closing segments altogether as near-zero visibility and spinouts blocked the roadway. Similar conditions were reported along U.S. 50 over Echo Summit and on Highways 88, 89 and 395.

The weather service in Reno warned that travel in the Sierra could be “very difficult to impossible” at times, with hazardous conditions likely to impact both weekend trips and the Monday morning commute.

The Sierra Avalanche Center issued a backcountry avalanche watch, saying rapidly accumulating snow and strong winds were creating unstable slabs on many slopes.

“A powerful storm with heavy snowfall and strong winds may cause widespread avalanche activity,” the center said. “Large avalanches capable of burying or injuring people are possible in backcountry terrain.”

One storm, opposite impacts—and a glimpse ahead

Atmospheric rivers are responsible for a large share of California’s annual precipitation and water storage, particularly in the Sierra snowpack. Scientists at the Center for Western Weather and Water Extremes at the Scripps Institution of Oceanography classify these events on a five-point scale based on strength and duration, from AR1, largely beneficial, to AR5, mostly hazardous.

This early-January storm fell in the middle, in the AR2 to AR3 range, with integrated water vapor transport values along the coast exceeding 500 kilograms per meter per second—a moderate to strong event by that metric. Forecasts called for 7 to 10 inches of precipitation in parts of the northern Sierra and Klamath Mountains and 4 to 8 inches in the central and southern Sierra and coastal ranges over the course of the storm.

As snow levels fell from around 8,000 to between 5,000 and 7,000 feet, more of that moisture began to accumulate as snow rather than rain in the mountains. State water managers and ski industry officials welcomed the boost after a slow start to the snow season.

On the coast, however, the storm’s timing against a backdrop of rising seas turned predictable king tides into a widespread flood.

Forecasters and coastal planners often describe king tides as a preview of future everyday high tides as global sea level continues to climb. Many of the streets inundated this weekend—including Miller Avenue in Mill Valley, Doherty Drive in Larkspur and parts of San Francisco’s Embarcadero—already see occasional nuisance flooding during winter storms. The near-record water levels reached Friday and Saturday pushed that nuisance into something closer to crisis for drivers, businesses and emergency services.

Officials said the weekend’s flooding was largely in line with forecasts issued days in advance. But with more atmospheric rivers expected later this winter, they urged residents to treat the event as a reminder to check evacuation plans, heed road closures and prepare for stronger storms.

By Saturday afternoon, as the tides began to recede and plows carved deeper canyons through Sierra snowbanks, the first atmospheric river of 2026 was still far from over. Rain and snow were forecast to continue into Monday. For California’s coasts and mountains alike, forecasters said, the coming days would test how well communities can live with both the water they need and the hazards that increasingly accompany it.