From the U.S. Coast Guard: 

20 foot or greater breaking seas have been observed at the entrance to Humboldt Bay Harbor. Due to these dangerous conditions, the Coast Guard is enforcing the pre-determined safety zones until seas are no longer breaking at 20 feet or greater in these locations. The Coast Guard will update information and we will relay it on social media as we receive it. Conditions are expected to ease on Saturday.

More info: During times of extreme environmental conditions temporary safety zones apply to the navigable waters of the Humboldt Bay Channel, Noyo River Channel, and Crescent City Harbor Entrance Channel. These safety zones will be enforced when on scene conditions reach 20 feet breaking seas or as the Captain of the Port determines that the on scene environmental conditions are hazardous and unsafe for vessel transits, as announced via Broadcast Notice to Mariners, all vessels are prohibited from transiting through or remaining in the safety zone.

Any vessel requesting permission to transit the safety zone during times of enforcement shall contact the Coast Guard on VHF-FM channel 16 between 6:30 a.m. and 10 p.m., or to Sector Humboldt Bay on VHF- FM channel 16 or at (707) 839-6113 if between 10 p.m. and 6:30 a.m.