Sargassum Forecast: Caribbean & Florida (September 2026 bulletin)
A free, independent summary of where Sargassum seaweed is washing up, sourced from the University of South Florida's Sargassum Watch System satellite bulletins. This edition summarizes USF's September 2026 bulletin, published September 30, 2026.
The 2026 season is easing after a near-record year
USF's September 2026 bulletin found Sargassum falling in every region except the western Caribbean, which held steady. The total across the Atlantic belt halved from August, which had already halved from July. Amounts everywhere but the East Atlantic are still above the 75th percentile for September (2011–2025), so beaching around the Caribbean and Florida's southeast coast continues, but less severely than in summer. With the peak over, USF expects 2026 to finish second only to 2025.
Where the seaweed is now
Severity is our reading of USF's September 2026 bulletin for beach travelers. USF itself warns its bulletins are general outlooks, not forecasts for a specific beach.
| Region | Status | Severity |
|---|---|---|
| Western Caribbean | Unchanged from August; still above normal for September | High |
| Eastern Caribbean + Lesser Antilles | Falling sharply, but still above normal for September | Moderate |
| Florida (SE coast + Keys) | Beaching continues, lighter than in summer | Moderate |
| Greater Antilles (Cuba, Jamaica, DR, PR) | Declining; periodic beaching on east-facing shores | Moderate |
| Gulf of Mexico (Texas + Louisiana) | Down to about a third of August, which was a third of July | Low |
| Eastern Atlantic | Within the normal range for September | Low |
The 2026 season month by month
Total Sargassum across the Atlantic belt, from the map totals in USF's monthly bulletins.
| Month | Total in the belt | What USF reported |
|---|---|---|
| June 2026 | 33.6 million metric tons | Gulf reached 5 million tons, nearly double its 2025 record; Caribbean at a record high for June |
| July 2026 | 25.5 million metric tons | Decline begins; Gulf still at a record high for July |
| August 2026 | 12.5 million metric tons | Belt total halved; Gulf down to a third of July |
| September 2026 | 6.0 million metric tons | Halved again; western Caribbean unchanged |
Beach destinations largely unaffected
- Bahamas (most islands — exposed Atlantic shores may see minor arrivals)
- Pacific coast of Mexico and Central America (entirely unaffected — different ocean basin)
- US Gulf Coast west of Florida (typically minimal)
- Bermuda (occasional drift only)
Note: Sargassum is a natural, episodic phenomenon. Even typically clear beaches can see surprise arrivals when winds and currents shift. Always check local conditions 24–48 hours before travel.
What travelers should know
Peak season is May–August
Sargassum influx into the Caribbean typically peaks between late spring and late summer. If you can shift travel to January–March or October–November, arrivals are usually much lighter.
Windward vs leeward matters
Sargassum beaches on the windward (east-facing) side. The west or leeward coasts of most Caribbean islands see far less accumulation. Book accordingly.
Resorts with cleaning programs
Many larger all-inclusives in Mexico and Barbados now run daily beach-cleaning crews and floating barriers. When booking, ask about Sargassum mitigation specifically — generic "beach maintenance" answers aren't enough.
Health considerations
Decomposing Sargassum releases hydrogen sulfide gas (rotten-egg smell). Travelers with respiratory conditions should avoid affected beaches during heavy influx. It is generally not dangerous to the healthy public, but is deeply unpleasant.
Outlook: the rest of 2026
USF's September 2026 bulletin expects Sargassum amounts in all regions to keep falling until possibly November, following the pattern of every previous year.
Beachgoers should expect continued but lighter beachingaround the Caribbean and along Florida's southeast coast. The Mexican Caribbean and the rest of the western Caribbean are the exception to watch: amounts there held steady from August to September.
Late autumn and winter are usually the cleanest months for Caribbean beaches. A new season normally starts building in early spring.
Authoritative sources and further reading
This page summarizes publicly available data. For primary sources, official bulletins, and real-time satellite imagery, consult:
- USF Sargassum Outlook Bulletin, September 2026 (PDF)
Primary source for this edition. Published monthly by the University of South Florida Optical Oceanography Lab.
- USF SaWS Project Page
Project homepage with near-real-time satellite imagery and archive of past bulletins.
- CARICOOS Sargassum Tracker (Caribbean Ocean Observing System)
Interactive tracking tool focused on the Caribbean basin.
- Sargassum Information Hub (CARICOM)
Regional monitoring consortium covering Caribbean member states.
- Caribbean Alliance for Sustainable Tourism — SaWS Resources
Travel-industry focused explainers and mitigation guidance.
How we compile this page
We read USF's Sargassum outlook bulletin (USF publishes one at the end of each month), summarize its regional findings and translate them into traveler-relevant guidance. The heading above names the bulletin this edition is based on, and the "Last updated" date shows when we last revised the page. We do not collect or manipulate the underlying satellite data — we cite it. For research use, always refer to the primary USF source. Corrections: email info@bestbeachreviews.com.
Sargassum forecast FAQ
Is there sargassum in Cancún right now?
Some, but far less than in summer. USF's September 2026 bulletin found the western Caribbean, which includes Cancún, Playa del Carmen and Tulum, unchanged from August and still above normal for the month, while every other region declined. Beach landings continue but are lighter than in June and July. Conditions shift week to week with wind and current, so confirm with your hotel 24–48 hours before arrival.
When is sargassum season in the Caribbean?
Sargassum influx into the Caribbean typically peaks from May through August, ramping up in April and easing by late autumn. January–March and October–November usually see the lightest arrivals, making them the safest windows for a clean beach.
Which Caribbean and Mexican beaches have the least sargassum?
The Pacific coast of Mexico (Puerto Vallarta, Sayulita, Los Cabos) sits in a different ocean basin and stays essentially clear. Most Bahamas islands, leeward (west-facing) Caribbean coasts, and the US Gulf Coast west of Florida see far less than windward, Atlantic-facing shores.
Is sargassum dangerous to your health?
Fresh sargassum floating in the water is harmless. As it decomposes on the beach it releases hydrogen sulfide gas (a rotten-egg smell) that can irritate the eyes and airways. Travelers with respiratory conditions should avoid heavily affected beaches during peak influx; for most healthy visitors it is unpleasant rather than hazardous.
Was 2026 a bad sargassum year?
Yes. With the peak past, USF expects 2026 to finish as the second-largest Sargassum year on record, behind 2025. The Gulf set a record: about 5 million metric tons in June, nearly double its 2025 high, and it was still at a record level for July. USF expects amounts to keep falling in every region until about November.
Does sargassum reach Florida and the Keys?
Yes. In 2026 USF reported severe beaching along Florida's southeast coast in June, when the Gulf held a record amount. By September beaching there was continuing but less severe than in summer. The Keys and the southeast coast (Miami, Fort Lauderdale, West Palm Beach) see the most; the season usually peaks in early summer.
Embed this on your site — free
Run a travel blog, resort, or dive shop? Drop this live Caribbean conditions widget on your site. It auto-updates with the latest sargassum and hurricane outlook — no maintenance for you.
Live preview
Copy & paste this code
<iframe src="https://www.bestbeachreviews.com/embed/caribbean-conditions" width="100%" height="540" style="border:0;max-width:520px" title="Caribbean Beach Conditions — Sargassum & Hurricane Forecast" loading="lazy"></iframe>Please keep the “Powered by BestBeachReviews” link intact. That's the only thing we ask in return.
Plan around Sargassum
Caribbean destinations
Browse Sargassum-affected and clear beach destinations across the region.
Best time to visit, island by island
Dry season, hurricane season and sargassum timing for each Caribbean island.
Book Sargassum-clear beaches
Search hotels on the leeward or Pacific coasts to avoid Atlantic influx.