A strong storm brewing offshore is causing breaking waves over 30 feet in some areas and creating dangerous ocean conditions.

As the ocean hammered the coast of California this week, video captured across the state made waves on the internet as observers took to social media to share dramatic footage of the heavy surf.

Late last year, a massive ocean swell ... generating it, the waves become swell and start to separate. The longest-period waves move fastest and shorter-period waves more slowly. Most waves resulting ...

A massive 12.34-metre ... "Those extreme waves are causing hazards to the coastal areas," BOM manager Matthew Collopy says. He warns the cyclone will bring a significant storm surge.

Late last year, a massive ocean swell ... The longest-period waves move fastest and shorter-period waves more slowly. Most waves resulting from a storm have periods of 12–16 seconds, with ...