The king tides that ravage the California coast every winter occur when Earth is at its closest to the sun.
By Quinn Welsch
As winter’s king tides returned this week, the global phenomenon offered a glimpse into the future of rising sea levels, drawing photographers, scientists, and locals to the California coast to document and to prepare.
It was 8:22 a.m. and the tide at Kendall-Frost Marsh was at its peak for the day. Most days, the 40-acre wildlife preserve on the northeast corner of San Diego’s Mission Bay is a vast, muddy wetland home to migrating birds and other wildlife. But San Diego’s king tides on Thursday and Friday pushed the wetland tides much farther inland than normal.
For the many photographers, conservationists, city officials and artists who converge at coastal areas like Kendall-Frost Marsh this time of year to document the tides across the California coast, it’s not just about sightseeing. For them, the king tides provide a naturally occurring model for the future of sea-level rise across the state.
Since 2010, the California Coastal Commission has asked volunteers, professionals and amateurs to photograph and document the king tides along the California coast to better understand what the future might look like.
The big waves show us what our coasts might look like as sea-levels rise and coastal communities start to disappear, according to organizations like the San Diego Bird Alliance, which hosted Friday’s king tides event at the marsh.
“It’s beautiful, but it’s also morbid because if we don’t do anything to make more wetland that is ready for sea-level rise — and if we don’t do anything to protect the wetlands that we have — then we will lose marsh as this becomes more and more common,” San Diego Bird Alliance conservation director Andrew Meyer told a small group at the marsh on Friday morning. “One of the important things we’re doing today is to take a photo of the infrastructure as it interacts with the high tide and add that to the coastal commission’s data set, so we’ll have long-term community science monitoring of this event as it gets a little higher every year.”
The average high tide at Mission Bay is 5.7 feet, but the tide’s 7.3-foot peak on Friday is similar to what we will see in the 2080s, Meyer said.
The median sea level is expected to rise by about 1 foot across the California coast by 2050, according to the 2024 State of California Sea Level Rise Guidance. By 2100, the median sea-level rise will increase by 3 to 6 feet, the report says.
That rise could have a profound effect on coastal communities across the state, according to the commission.
The king tides are forecast again Saturday, and then again on Jan. 2–3.
The big waves are the result of various different gravitational effects on Earth’s tides during the months of November, December, January and sometimes February.
Both the sun and the moon influence Earth’s tides, though the moon’s gravitational pull is about twice as strong. These gravitational pulls are more pronounced when the three bodies are aligned.
This alignment happens about twice a month, during the full moon and new moon, in what are known as spring tides. Big waves also occur when the spring tides coincide with the moon at its closest position to the Earth, known as its perigee.
But king tides add an extra layer to this cosmic equation. They occur when Earth is also at its closest point to the sun, during the winter months.
These tides come crashing into cliffs and seawalls, sometimes even spilling onto roads. Likewise, the low tides are much lower than normal during these events.
“It really helps someone understand the impacts and the reality of the situation rather than a graph or chart,” said Annie Frankel, who oversees the king tides project for the California Coastal Commission. “More practically, these photos help communities plan. It shows what is vulnerable to flooding now and in the near future so they can make educated plans. It helps scientists validate sea-level model rises so they can see what happens when the water level is about a foot higher. It is creating a record of change for our coast.”
It’s not just beach homes and expensive resorts that are threatened, Frankel said. The rising tides would have cascading effects on roads, infrastructure, groundwater availability and recreation areas too.
“You can see what a water level looks like at a higher level, and that might mean your favorite beach is underwater,” Frankel said. “You may see flooded roads every day. These places may not be available to us anymore.”
Beach erosion is also a major concern for the Surfrider Foundation, an environmental nonprofit that also participates in the king tides documentation. According to the Surfrider Foundation’s State of the Beach Report, about 70% of California’s beaches and about 50% of all beaches in the United States are expected to disappear as a result of sea-level rise by 2100.
The foundation works on finding what it describes as nature-based solutions to the rising sea level. Those include strategies to protect, restore and sustainably manage sea-level rise, such as planting dune grass to stabilize erosion.
“We’re actively working with city and county and state on coastal policies as far as construction goes,” San Diego Surfrider Foundation chairman Tom Cook said. “We are advocates for what’s called managed retreats — that’s where you’re moving public infrastructure off of the beach and the coastal areas — in response to extreme erosion.”
One such example the Surfrider Foundation hails as its gold standard for managed retreat is Surfer’s Point in Ventura, California. Starting in the early ‘90s, the foundation was able to successfully restore portions of the shoreline, bike path and parking along Surfer’s Point. The project is expected to complete in early 2026.
The annual photos of the king tides help groups like the Surfrider Foundation make similar plans.
“We can kind of imagine what our coastlines are going to look like with the advent of sea-level rise,” Cook said. “It gives us an opportunity to assess areas where we may have erosional hot spots.”
The tides also give environmental groups an excuse to get outside and meet with each other.
The San Diego Surfrider chapter organizes similar events like community bike rides and beach cleanups in the area, Cook said.
The San Diego Bird Alliance organizes similar events at the Kendall-Frost Marsh, including education outreach for children and habitat restoration. Friday’s event also included plein air painting with the Urban Sketchers of San Diego to document the tides, as well as its first binational partnership with the Mexican-based birding group, Programa de Aves Urbanas, in Tijuana.
Photographers who want to participate in documenting the king tides should make sure that they stay safe during the events, most importantly, and to be mindful of any wildlife taking refuge from the waves, Frankel said.
“If you’re going out to take photos, don’t lose sight of the ocean,” she said. “Be careful of where you’re standing.”
She also said context is more important than dramatic images.
“It’s a good photo if there’s something in it that’s stationary, like a seawall, or road or bluff, or stairway so we can understand the height of the water,” she said.
Photographers should plan to document the tides within 30 minutes of their scheduled peak.
Photos of flooding on roads, in neighborhoods, or other similar events are also encouraged, Frankel said.
Photographers using smartphones should ensure that their location services are enabled on their camera app, so they can document the precise location of the photo, she added.
Photographs of the king tides can be uploaded to the California Coastal Commission from a web browser or from the Survey123 app.
“We really appreciate people’s participation in this project,” Frankel said. “It’s only possible when average people go out and tell us what they see. I encourage people to also enjoy their time at the coast. It gives you a reason to get outside, enjoy the beauty of our coast, share what you see with other people over the holidays and talk to them about what you noticed and what you’re concerned about. That conversation can have a big impact.”
More details about the king tide events can be found on the California Coastal Commission’s website.
