They're called "King Tides."
And they're making an appearance along the Southern California coast early this week. "King Tides" are astronomically caused - it's when the moon, sun and the Earth are all in alignment together with the moon being the closest to the planet. There's a strong gravitational pull and tides can reach as high as seven feet tall.
Advisories have been issued today for coastal areas in Southern California and up in the Bay Area.
In Southern California, John Pope from the City of Newport Beach says while high tides are nothing new the city is getting ready for the worst case scenario.
"We have a sand berm along the peninsula that is built up and maintained this time of year to stop any flooding from coming up and over into the community so that is our first line of defense," he says.
So far, Newport Beach has not experienced any damage from high tides.
For one, the City of Seal Beach tells KNX 1070 News it's currently building sand berm and prepping for potentially high water levels.