Large surf and high astronomical tides are arriving together along the San Diego County coast, prompting the National Weather Service to place local beaches under high-surf and coastal-flood advisories from 6 a.m. Saturday through 11 p.m. Tuesday. The overlap extends across the Labor Day weekend, when more people are likely to be near the water.
Forecasters expect breaking waves of 6 to 10 feet at south- and southwest-facing beaches and 4 to 7 feet along west-facing shores. Those separate ranges mean the maximum in the advisory is not a countywide wave height. The direction a beach faces is part of the Weather Service's forecast for where the largest breakers will arrive.
The same surf that raises breaker height also strengthens rip and longshore currents. Rip currents carry water away from the beach through channels in the surf zone; longshore currents move parallel to the coast. Both can shift quickly around structures and sandbars, so a shoreline that looks manageable between sets can become hazardous when the next group of waves arrives.
Flood risk will concentrate near the day's highest tides. The Weather Service lists La Jolla predictions of 6.0 feet at 4:48 p.m. Saturday, 6.3 feet at 6:03 p.m. Sunday, 6.7 feet at 7:03 p.m. Monday and 6.8 feet at 7:54 p.m. Tuesday. Each peak comes later and higher, extending the period when waves can run farther up beaches, lots and low roads.
The coastal-flood advisory calls for minor flooding of parking areas, parks and roads, with isolated road closures possible. Beach erosion is also expected. Those impacts depend on the timing of the larger wave sets relative to high tide; the advisory describes a hazard window, not a promise that every listed site will flood.
For beachgoers, the Weather Service advises inexperienced swimmers to remain out of the water, everyone entering the ocean to stay near a lifeguard, and visitors to keep off seawalls and jetties. People setting up on the sand should move farther back than usual and avoid turning their backs on the ocean because individual waves can travel beyond the apparent wet line.
Drivers face a different limit. The agency says not to cross barricades or water of unknown depth and to allow extra time if roads close. Coastal flooding can leave debris or hide the pavement edge even when water appears shallow. Moving a vehicle or protecting flood-prone property before the tide peaks is safer than attempting either task once water is already across a route.
The advisories were updated shortly after midnight Saturday by the Weather Service's San Diego office. Conditions will not be uniform for all four days, and actual breakers depend on local bathymetry and swell arrival. Residents should use current lifeguard instructions and subsequent Weather Service updates rather than treating the maximum forecast height as a constant condition.
Tuesday evening's 6.8-foot predicted tide is the highest in the listed sequence, near the end of the advisory period. The hazard therefore does not end with the holiday weekend. The coast will continue responding to the combination of swell direction, shore shape and rising tides after many visitors have returned to work or school.