Big wave surfing is a term you usually hear associated with Hawaii’s North Shore, not Northern California. There is one spot though, off Pillar Point near Half Moon Bay, where the waves were considered too big for locals for a long time. One local, Jeff Clark, decided to brave the waves in 1971 and thus became the first documented surfer to catch a wave at Mavericks, the surf spot just off Pillar Point. He enjoyed this hidden surf gem in near exclusivity until 1990 when a friend of his, Steve Tadin, was photographed at Mavericks and appeared in Surfer magazine. Mavericks starting gaining some real recognition then, and it has been building ever since.

The invitation only competition at Mavericks began in 1999, attracting some of the biggest names in surfing. In the beginning, competitors received only one day’s warning before the competition would be held. Since 1999, the technology has improved for predicting storms, and by extension; waves, so there is now a 3-4 day notice for surfers and spectators. The contest was suspended due to unusually mild conditions in 2007, 2009, 2011 and 2012. Since the nearby Northern California surf spots don’t have these monster waves, what creates these huge swells in one spot? We did some research and dove into the data to find out a little more about it.

First, some background on how waves are formed in a very simplified version. The waves off Pillar Point are a product of the “wave factory” of the North Pacific. The Gulf of Alaska is a hot bed for storms, making it an ideal spot for energy to be transferred from the storm, onto the surface of the water, creating waves that travel all the way to the coast of California.

Thanks to the unique underwater topography at Mavericks, a wave is refracted, meaning the energy across the entire wave is bent into a V. The energy of a longer wave is conserved and focused into a smaller area, meaning the only way for the wave to go is up, creating the big waves at Mavericks that can get as large as a four story building, and when some of these waves come crashing down, they register on the UC Berkeley seismograph. That’s right, the waves actually shake the North American plate.

The Mavericks season begins in November, and runs until about March. The invitational contest began November 1st of this year and from the graph below, you can see why surfers flock to the area within this time frame. This graph represents the average wave heights by month from 2003-2012. The best way to measure wave heights is actually the topic of some debate. The data you see below was collected from the National Oceanic and Atmospheric Administration’s buoy just off the coast of Pillar Point, but the wave faces the surfers ride can frequently be double the buoy-measured height.

You can also get a very rough idea of why the contest didn’t run in 2007, 2009, and 2011. The season for Mavericks started strong in 2007 but did not fulfill the hopes of big waves surfers as the season wore on. As the Mavericks season spans two different years, in this case the years mentioned refer to the second year in the season. For example: the 2007 season is considered November 2006-March 2007.

To get a bit better idea of wave heights that surfers compete on, take a look at the average wave height on the days when the contest was held. In 2010, just the average wave height was nearly 5 meters, with reported wave faces being upwards of 10 meters (nearly 40 feet).

You can also see how greatly the max and min wave heights vary throughout the contest day:

The quality of big waves is determined not just by their height, but also by their period. The dominant wave period is characterized by the waves with stronger energy, the waves surfers are more likely to be riding. The average wave period is significantly shorter than the dominant wave period, as you can see below. The length of periods follow the same trend as wave height, confirming that November – March are the best months for huge waves.

Play around with this dataset yourself and see what you can find out about Mavericks using DataHero. If you’re in the Northern California area, you can also sign up to be notified when the contest organizers announce when the contest itself will start and watch surfers tackle these big waves for yourself.