Since 1991, I’ve been forecasting waves along the Central Coast, and this recent swell event was the longest period/wavelength I’ve ever witnessed. The waves were heavy, breaking with incredible force. I captured these photos at Estero Bluffs State Park on Monday, December 23.
I received several emails—mostly from surfers—inquiring about a study published in Nature Communications by the Institute of Marine Sciences at UC Santa Cruz. The study found that wave power has increased globally by 0.4% per year since 1948, correlating with rising sea surface temperatures.
About eight years ago, I wrote a column on increasing wave energy, drawing from data collected by the waverider buoy at Diablo Canyon Power Plant. This buoy, deployed along the Pecho Coast (between Point San Luis Lighthouse and Point Buchon), has been in operation since June 1983—making it one of the longest-running wave monitoring stations on the West Coast.
Over the past 40 years, Diablo Canyon Waverider buoy’s data archive at the Coastal Data Information Program (CDIP) at Scripps Institute of Oceanography shows about a 5% increase in long-period wave events. This trend is directly linked to more intense storms in the Pacific, characterized by lower air pressures and stronger winds.
On December 20, a mid-latitude cyclone near the international dateline rapidly intensified, dropping from 973 millibars to 941 millibars (27.79 inHg) in just 12 hours—a remarkable 32-millibar drop, far exceeding the 24-millibar threshold needed to classify a storm as a “bomb cyclone.” Based on wave spectral analysis from the Diablo Canyon buoy, the storm may have been even more intense than surface charts and models suggested.
Unfortunately, NOAA marine buoy #4605 – WEST CALIFORNIA was out of service, limiting the accuracy of the wave forecast.
The trend of longer-period, more powerful swell events is expected to persist as the planet continues to warm.