Last week in Marin County, California, significant flooding from heavy rainstorms and king tides impacted the community. On Saturday, Jan. 3rd, the king tide event broke a 27-year-old record across parts of California. With the recent atmospheric river-related damage to Washington state and the record-breaking tides in California, now is a crucial time to understand water hazards. So, what is a king tide?  

The term “king tides” is an informal way to describe these large tidal events. According to NOAA, the term is used to describe exceptionally high tides caused by the gravitational alignment of the Earth, moon, and sun. They occur when:

• The moon is either full or new.
• The moon is closest to Earth (a point known as perigee)
• There are specific seasonal factors, like winter storms and low atmospheric pressure.

Chandler Countryman, a specialist at Washington Sea Grant, provided insight, saying, “King tides are fairly easy to predict. King tides, like ordinary high and low tides, are astronomical tides, meaning they are caused by the gravitational pull on the oceans by the Moon and the Sun. The larger the gravitational pull, the larger the tidal range will be.”

However, King tides can also contribute to flooding. As in the case of Marin County, King tides are known for bringing unusually high water levels, and combined with sea level rise, understanding and predicting these events are becoming increasingly important for local coastal communities. 

Countryman continues saying, “What can be less easy to predict are weather events that may coincide with a King Tide that can impact the total water level experienced in a coastal area.”

“Naturally occurring King Tides are a great way to visualize what sea level rise will look like in our communities. The King Tides of today will be our everyday high tides in the near future. We can use lessons learned from current and past flooding events that occur during a King Tide to help us better prepare in the future. And people all across Washington’s shorelines can help scientists and decision-makers better understand these flooding impacts by uploading photos to the MyCoast App.”

If you encounter flooding during a King tide event, please report it. Community reports help improve real-time awareness and long-term flood preparedness. You can submit flood observations through our iFlood page or directly through the iFlood website. 

Additionally, Countryman talked about the Washington King Tides Program, “the program invites people to visit the shoreline during a King tide or high water event while taking precautions to be safe. It is helpful to take pictures of important waterfront locations in your community where the impact of the tide can be gauged against familiar landmarks that do not move with the tides, like buildings, roads, sea walls, and beach infrastructure such as boat ramps, piers, and pilings. These images help scientists, local planners, and decision-makers understand how sea-level rise and storm surges affect our infrastructure and ecosystems.” Similar programs exist in Oregon and California. For further information on the Washington King Tide Program, visit the program’s website here.

Winter King tides remind us of how powerful, dynamic and changing the ocean is. By staying informed and sharing what we see, we can better prepare our coast for what lies ahead.