A perspective for the Caribbean Sea and Gulf of America* by the University of South Florida Optical Oceanography Lab – (bbarnes4@usf.edu, yuyuan@usf.edu, huc@usf.edu)

The map above shows the average Sargassum abundance for the month of January 2026, with warm colors representing higher abundance. The top color (red) indicates that 0.4% of the ocean surface is covered by Sargassum, meaning that Sargassum clumps and mats are scattered here and there in the location. The Sargassum abundance for each region is compared with historical values in the same month of 2011 – 2025 in the whisker box plot below, where horizontal bars in each vertical box indicate minimum, 25%, 50%, 75%, and maximal historical values, respectively.

As predicted last month, Sargassum in the Caribbean continued to grow, from 0.45M tons in Dec 2025 to 1.7M tons in Jan 2026. The Gulf also showed measurable Sargassum of 0.2M tons, mostly to the north of the Yucatan channel. While the E Atlantic remained stable, the W Atlantic saw a substantial increase from 4.1M to 5.5M tons. Except for the E Atlantic region, every other region saw record-high Sargassum amount for the month of January. The distribution map shows three separated large masses in the E Atlantic, W Atlantic, and the Caribbean, respectively. Some regions in the W Caribbean, including Belize, Honduras, and the Mexican Caribbean coast, should have already seen some beaching events.

Looking ahead: As in the past years, Sargassum amount in most regions is likely to increase in the coming month. The W Caribbean will continue to see beaching events in some regions. Some of the Lesser Antilles islands may start to see beaching events. Because of the continuous growth from November to January and because of the record-high Sargassum amount in most regions, 2026 is very likely another major Sargassum year (i.e., Sargassum amount exceeds 75% of the historical values). All previous monthly bulletins as well as daily imagery can be found under the Sargassum Watch System (SaWS). Meanwhile, we will keep a close eye on Sargassum changes in all regions.