This round of king tides on Northern California coastline will be the king of them all

Drivers navigating the entrance onto the westbound direction of the Bay Bridge during the commute Friday morning had something other than traffic to stress them out — water from the San Francisco Bay flowing onto Interstate 80 near the metering lights and toll plaza.

The third round of king tides since November arrived Friday, coinciding with a set of storms that started to drop rain Wednesday and won’t stop doing so until Monday afternoon, according to the National Weather Service.

The region also saw king tides in early November, and another round of them in early December.

This week’s tidal event is expected to be in a class of its own. Meteorologist Roger Gass said Friday that areas of land that are normally dry could be 2½ feet under water.

The king tides are caused by celestial events including the position of the moon and sun. According to experts, the higher tides come when the earth, the moon and the sun all align in a straight line, bolstering the combined gravitational pulls of the moon and the sun.

These tides are receiving an extra boost because the full moon right now is a so-called “super moon,” when the moon is nearer the Earth during its orbit, experts said.

“This is going to be the maximum tide for the whole year,” meteorologist and weather consultant Jan Null said. “Everything is lining up at once. It’s not going to be end-of-the-world sorts of stuff. All of the lower-tier parking lots will probably be covered with water. Maybe some of the upper-tier ones, too.”

The weather service issued a coastal flood warning along the San Francisco Bay Shoreline that’s in effect through 2 p.m. Saturday. Among the cities expected most to be affected by the king tides are San Francisco, Pacifica, Half Moon Bay and other communities along the coast in San Mateo County. Low-lying areas of Alameda, Contra Costa and Santa Clara counties also are in harm’s way, with those areas including parts of Berkeley, Richmond and San Pablo.

“We aren’t any strangers to this,” Pacifica police spokesperson Capt. Bill Glasgo said Friday. “Where we get the issues are from the people who aren’t from here that come to witness (the waves). They stand close to the edge and the guard rails, and they get pummeled by the waves that come over. … Our community is well aware of these folks, and a lot of time peer pressure and residents who are out and educate them are generally the best deterrent.”

The tides will be crashing amid rain that is expected to begin again Friday night and last into Saturday before resuming again on Sunday after a brief break. Null said it’s likely that the places most susceptible to rain — the North Bay and Santa Cruz Mountains — could get as much as 4 inches of rain in a 96-hour period, while Alameda, Contra Costa and Santa Clara counties are more likely to receive 2 inches.

By 2 p.m., the tides and rain had combined to create issues in Marin County. Social media video showed free-flowing waters along streets in Mill Valley at about 9:30 a.m. Friday, and cars on the Bay Bridge having to navigate the toll plaza amid rising water.

Flooding also affected traffic on westbound I-980 on the transition to southbound I-880 to the Jackson Street exit and on eastbound I-580 at the Berkeley Curve, the California Highway Patrol said.

Officials urged motorists to avoid driving past marked areas and to stay off the roads if they can. Beach-goers should stay away, authorities said.

The extreme high water is expected to recede beginning Sunday, when weather experts said the official period for the maximum king tides end.