That is when high tide is a foot or more higher than average. Monday morning's high tide in San Francisco is expected to be 6.9 feet at 8:59 a.m. The average high tide is 6 feet at Aquatic Park -- the oldest continuing tidal observation station in the U.S.
Michael Bank waded through water that used to be the walkway to his Sausalito houseboat. Its ritual he's done before.
"I mean, what can you do? I mean, it's water, it's the bay. So, you just, you buy boots," said houseboat resident Bank.
The king tides arrived in Sausalito Monday morning, quickly filling this parking lot with water.
Fred Altman decided to sandbag the entrance to an office building to keep the high tides out.
"Well, all the electronics would get ruined. The flooring would all get ruined. So, it would be expensive," said Altman.
Houseboat residents are checking their phones for tide schedules; they know king tides will stick around for the final days of 2013.
"We parked our vehicles on the other side over here and, you know, warn each other that the high tide is coming. And, kind of take care of each other around here," said houseboat resident Richard Charles.
The California Coastal Commission says king tides are a winter phenomenon, which happens when the gravitational pull of the sun and the moon are in alignment.
"It's a little higher. It's no big deal, you know, you just deal with it. That's what you have to pay for living in utopia," said Bank.
King tide heights and times may vary in other parts of the Bay Area.