The National Weather Service extended its coastal flood advisory for the San Francisco Bay through Thursday morning, warning of maximum inundation reaching 1.9 feet above normal during high tide — while a separate beach hazards statement flags sneaker waves and rip currents along the Pacific Coast through the same window.

A convergence of elevated tides, wind, ocean swell, and thermal expansion is generating a rare triple-threat along the Bay Area coast this week: bayshore roads and parks flooding at high tide, hazardous surf conditions along ocean-facing beaches, and a heat advisory pressing down on inland areas — all running simultaneously through the middle of the week.

The National Weather Service San Francisco Bay Area office extended its Coastal Flood Advisory by one day on Monday, pushing the warning for San Francisco Bay communities through Thursday morning. The advisory for Pacific Coast beaches runs through Wednesday morning, according to NWS.

The flooding is driven by an unusual combination: abnormally high astronomical tides amplified by wind, ocean swell, and thermal expansion. At the San Francisco tidal gauge, the NWS projects tides to reach 1.8 feet above normal in the early hours of Tuesday, 1.7 feet above normal early Wednesday, and 1.2 feet above normal early Thursday. Further south, the Monterey gauge is expected to peak at 2.0 feet above normal Monday night and 1.8 feet above normal Tuesday night, per the Bay City News report on the advisory.

Bayshore communities from the North Bay to the South Bay face the greatest exposure. The NWS warned that minor coastal flooding could affect roads, parks, and parking lots in low-lying areas, with isolated road closures possible. Maximum inundation during high tide is forecast at 1.9 feet, according to the NWS website. Officials are urging drivers not to go around barricades or drive through standing water.

Ocean-facing beaches are contending with a separate but simultaneous hazard. The Beach Hazards Statement — also extended through Thursday morning — covers a long-period south-southwest swell that the NWS says will generate sneaker waves and strong rip currents. According to the agency's briefing, south and southwest facing beaches carry the greatest risk. Hazardous beach conditions are expected across coastal sections of the North Bay, San Francisco, the Peninsula, Santa Cruz County, and Monterey and San Benito counties.

"Long-period S-SW swell will generate hazardous conditions at the beach, including sneaker waves and strong rip currents," the NWS wrote in its advisory. "Stay back from the water's edge, stay off of jetties and piers, and NEVER turn your back on the ocean."

Sneaker waves — sudden surges that wash far higher up the beach than recent waves — can strike without warning and have been responsible for multiple deaths along the Northern California coast in recent years, including incidents near Baker Beach and Pacifica.

Inland areas face a third front: the NWS is also tracking minor to locally moderate heat risk through midweek, particularly in warmer inland valleys. Cooler conditions are expected to arrive later in the week as the weather pattern shifts.

The advisory comes two weeks after a Putah Fire heat event scorched Yolo County during triple-digit temperatures, and less than a month after lifeguards at Baker Beach pulled swimmers from the surf on back-to-back days following dangerous shorebreak conditions — incidents The Dissent reported on in May.

Residents along the bayshore should monitor tide forecasts closely and expect possible disruptions to low-lying parking and waterfront access through the week's end. Beachgoers are advised to stay well back from the water's edge at ocean-facing beaches and to treat any unexpected surge as a sneaker wave threat.