With the moon and sun aligned to give the seas an extra gravitational kick onto shore, some low-lying areas saw a touch of flooding on Wednesday, the day before the so-called "king tides" peak on Thursday.

In Redwood City, an industrial area near Maple and Blomquist streets saw about 18 to 20 inches of flooding, according to city spokesman Malcolm Smith, who noted that no homes were damaged or people harmed. San Mateo County officials don't expect water-related woes when the tide peaks around 11:30 a.m. Thursday, lapping just slightly higher than it did Wednesday.

High water was also seen in Sausalito, where flooding forced the closure of a freeway offramp and in the area around Lake Merritt in Oakland, where a pedestrian tunnel filled with two feet of water.

"I don't think the minimal rainfall we saw had anything to do with the flooding," said National Weather Service forecaster Bob Benjamin. "I think it was almost exclusively reflective of the high tides."

Larry Smith, a weather service meteorologist, said expected conditions shouldn't exacerbate the tide in coming days. Within the San Francisco Bay, Smith said, the main concern would be a strong wind driving water ashore, while coastal communities need to also be wary of the ocean swell.

Thursday's forecast for the Bay Area called for mild winds in the morning when the tides are highest, picking up sometime in the afternoon when the water is already receding. And since the surf's not up along the coast from Half Moon Bay to Ocean Beach, conditions won't give king tide extra ammo when it storms the beaches. Friday could bring a slight chance of showers, he said, but by then "tides will be on a downward trend."

Smith didn't know of any expected trouble spots, but said that the weather service will be monitoring what happens for future reference.

"If it would have been last week with all the heavy rains, it could have been a bigger deal," Smith said. "With the rain running off the hills into the bay and drains overflowing, you add the tidal surge onto that and it could have been a lot messier."

The gravitational tug of the moon and sun cause extreme tides that occur several times a year, although this week's are the biggest of 2012.

Along with the high-water marks this week -- from a few inches to several feet above than normal, depending on the location -- there are also extremely low tides.

At Half Moon Bay on Thursday, for example, the high tide is expected to be plus-6.8 feet at 9 a.m., or 6.8 feet above the historic average daily low tide. The ocean will then fall 8.5 feet by 5 p.m. that day to a minus-1.7 feet tide, which means tide pools should be full, exposed and ripe for exploring.

In Berkeley, harbormaster Ann Hardinger cautioned boat owners to let the leash out when mooring at the docks to allow watercraft to rise with the highs and go with the lows.

"Make sure your (rope) lines have plenty of slack and keep them off the pilings, tie them up to the cleats on the dock," Hardinger said.

In Oakley, Chris Lauritzen, of Lauritzen Yacht Harbor called it "a whole lot of nothing."

"We've seen way higher water than this 'king tide' before," he said, but agreed it would have been a different situation last week. "We'd all be swimming around and having no fun at all if that were the case. ... This really is a nonevent."

As they have for the past two years, a coalition of government agencies and nonprofit groups is asking the public to take photographs Thursday around California to document the high water -- preferably of the same place at high tide and low tide.

For more information about the California King Tides Initiative photo project, which posts the photos online, go to www.californiakingtides.org.

Bay Area News Group reporters Joshua Melvin, Kristin J. Bender, Katie Nelson, Doug Oakley, Peter Hegerty and Paul Rogers contributed to this report.