NWS Forecast Office San Francisco, CA

A very long period WNW swell will impact the Sonoma to Big Sur coast through the day on Wednesday and persist into Thursday. A high to extreme risk of sneaker waves will exist during this timeframe. The largest energetic sneaker waves will arrive irregularly every few minutes to as infrequently as once every 30 minutes during otherwise deceptively calmer seas and consequently may catch those on coastal jetties, rocks, piers, or shorelines off-guard and may injure them or knock them into the cold, turbulent ocean. Beachcombing is not advised during this timeframe. In addition, strong rip currents will accompany the energetic wave train, particularly at WNW facing beaches. These type of events claim lives each year along our coast so extreme vigilance is advised if visiting the coast. Finally, moderate to locally large breaking waves of 14 to 18 feet will be possible later in the day on Thursday at WNW facing beaches as the swell period decreases and swell heights increase, thus this product will be in effect through the day Thursday.