PLAYA DEL REY, CA — It’s getting darker earlier, and when the sun falls you now have a chance to watch the return of stunning blue, bioluminescent waves in Southern California.

The waves started reappearing over the last three weeks in the Santa Monica Bay in Los Angeles, according to the Los Angeles County Fire Department Lifeguard Divison.

The algae bloom, known as a “red tide” is bioluminescent, and it glows when microorganisms are agitated by splashing or by waves.

(Nicole Charky/Patch)

The phenomenon is caused when large numbers of dinoflagellates form a bloom. Dinoflagellates use bioluminescence as a predator avoidance behavior, according to bioluminescence expert Michael Latz, a scientist at Scripps Institution of Oceanography at UC San Diego.

Red tides are unpredictable, and they don’t occur in Southern California every year.

“Pinpointing when and where this phenomenon takes place is difficult, however, it is quite a sight to see if you are able to witness it,” the Los Angeles County Fire Department Lifeguard Divison said on Instagram.

Patch Asks: Have you seen the blue, bioluminescent waves?