King Tides reveal the future of sea-level rise

If you went outside on the night of January 20, you may have seen a deep-red full moon, an eclipse by the Earth creating a dark shadow on the its surface. This lunar event not only made for a spectacular sight, but also influenced the ocean’s tides.

Communities living along coastlines experience the sloshing in and out of seawater throughout the year, with the highest water levels of the year coined “King Tides.” King Tides occur when a combination of astronomical events cause a strong gravitational force on the Earth. Events that create these expanded tidal events include

Perigean: the moon’s monthly orbit is closest to Earth.

Perihelion: the earth’s orbit is closest to the sun (annually around January 2).  

Syzygy: the moon, earth, and sun align.

Spring tides: high and low tides have the greatest difference between them following a full or new moon.


King Tides can be exciting events to observe, but they can also flood roads damage infrastructure, especially if a King Tide co-occurs with a storm that brings additional wave energy and freshwater into the equation. King Tides also give us a picture of what higher sea levels may look like as our planet adapts to a changing climate. To put it simply, the tides that we see during King Tides could become our normal high tides in the future.

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Slough area next to Willapa Landing. The photo on the left was taken near low tide, and the photo to the right taken near high tide. Photos by Sean Galvin.

Preparing today with resilient coasts

Connecting today’s conditions along the coast with projected sea-level rise is a part of the Washington Coastal Resilience Project (WCRP), a 3-year project funded through a NOAA Coastal Resilience grant and implemented in collaboration with state, federal, and environmental agencies.

Washington Sea Grant and the UW Climate Impacts Group developed more than 170 localized projections of sea-level rise. We’re now using these data to support Washington’s coastal communities as they integrate them into planning, education and community development. At the recent King Tide, we joined a Sea Grant event in Grayland and Raymond to educate community members and listen to their concerns about future flood risks.  

Community connections allow TNC and our partners to help prepare residents for rising seas on Washington’s coast. Photo by Sean Galvin.

Community connections allow TNC and our partners to help prepare residents for rising seas on Washington’s coast. Photo by Sean Galvin.

Today’s tides provide a glimpse for years ahead

Many of the community members we spoke with are already facing issues with erosion and flooding, putting road travel and developments at risk. One family who had recently moved to the area described their shock as roads and highways flooded during high tide events, including their route to school. If the roads are already flooding now, they fear, what does this mean for a future where the tides continue to rise?

In Grayland, on a given day, the mean higher high water is 8.18 feet. On January 21, the high tide hit 11.20 feet, an increase of more than 3 feet. WCRP’s projections for Grayland show sea-levels rising 0.6 feet by 2060 aond 1.2 feet by 2100—and that is the most conservative projection using a low-emissions scenario. Raymond experienced a high tide of 12.26 feet during January’s King Tide--exceeding the mean higher high water by 2.44 feet. In the low-emissions projection, sea levels in Raymond are expected to rise 0.8 foot by 2060 and 1.5 ft by 2100.  

Risks grow as our climate warms but we are raising awareness not to share alarming information, but rather to empower communities. With science and outreach, WCRP provides pivotal guidance so that Washington’s coastal residents can sustainably adapt to protect their homes and communities.

To learn more about King Tides and to get involved in preparing for sea level rise:

  • Visit Washington Sea Grant’s King Tides Program website.

  • Visit and/or download the MyCoast: Washington application, to upload reports and photos of King Tide inundation. Collected information is used by Washington Department of Natural Resources and partners to view the impacts of flooding and to inform decision makers.

  • Contact your local city or county planners or planning commissions to voice your concerns about current and future flooding.

  • Engage with your city or county’s Shoreline Master Program or Comprehensive Plan updates.

  • Go to the Washington Coastal Hazards Network website to view more information on coastal hazards and the latest science on sea level rise.