The rare sighting is part of the cold weather system that's making its way down into Southern California.
The National Weather Service noted that the cloud is not a tornado because it didn't make contact with the ground.
Some people took to social media to share photos and video of the cloud.
There have been several reports of funnel clouds along the coast today. Here's the most recent one from #Carlsbad captured on video. Note: Not a tornado, as this requires contact with the ground. #cawx https://t.co/kPpZefgLCB— NWS San Diego (@NWSSanDiego) December 31, 2018