Moderate coastal flooding is possible along Bay Area shorelines through Sunday, while light rain could reach parts of the region Saturday, according to the National Weather Service.
In an advisory early Friday, the weather service warned that high tides could flood low-lying areas, cause isolated road closures and contribute to coastal erosion. Rising water and waves could also reach farther up beaches than usual, making it harder for people to leave coastal areas safely. The coastal flooding risk extends along the shores of San Pablo, San Francisco and Monterey bays, as well as the Pacific coast.
At the San Francisco tidal gauge, high tide is expected to reach 1.9 feet above normal at 2:39 p.m. Friday. The level is forecast to reach 1.5 feet above normal on Saturday afternoon and a foot above normal on Sunday afternoon.
The tide forecasts include about 1.5 feet of additional water from surge effects linked to thermal expansion and low pressure. High tide times can vary by as much as 90 minutes along the coast and throughout San Francisco Bay, forecasters said.
A 30 percent chance of rain, meanwhile, is projected for Saturday in Piedmont, mainly after 11pm. Conditions on Halloween are expected to be mostly cloudy, with a low around 49 degrees and a light west wind.
The weather service said rain could return next week, with seasonal to slightly below seasonal temps expected through the extended forecast. Residents near the coast are advised to allow extra travel time because of possible road closures, avoid driving around barricades or through floodwaters of unknown depth, and take steps to protect property from flooding.