USF / NASA Alert: Second consecutive monthly doubling of Sargassum !


Outlook of 2023 Sargassum blooms in the Caribbean Sea and Gulf of Mexico*
February 1, 2023, by University of South Florida Optical Oceanography Lab

The maps below show Sargassum abundance, with warm colors representing higher values. The overall Sargassum quantity in the Atlantic Ocean doubled from December to January (8.7 million tons), again setting a new record (previous January record was 6.5 million tons in 2018). Sporadic Sargassum patches appeared in the Lesser Antilles near the month’s end, with larger aggregations passing south of Martinique. Within the Caribbean Sea (CS), most patches were south of Jamaica, moving westward over the course of the month. Essentially no Sargassum was observed in the Gulf of Mexico (GoM).

Looking ahead, this is the second consecutive monthly doubling of Sargassum, previously observed only in 2018. All indications are that this biomass will continue to accumulate and migrate westward over the next several months. We will continue to closely monitor Sargassum coverage, with more updates provided by the end of February 2023. More information and near real-time imagery can be found under the Sargassum Watch System (SaWS,

Processing note: For this and future bulletins, we have transitioned to a new Sargassum detection algorithm which leverages machine learning. Relative to the previous method, this new approach shows near-identical sensitivity in detecting Sargassum, while reducing false positives and false negatives near clouds and shorelines. While overall quantities slightly differ, relative trends noted in this (and previous) bulletins are the same for both systems.