Caribbean sargassum dataset: how often seaweed reaches each stretch of coast, month by month

Name: Caribbean sargassum: monthly nearshore record by stretch of coast, 2016–2024
Creator: Veabird
License: https://creativecommons.org/licenses/by/4.0/

A free, open record of nearshore sargassum for 189 stretches of coast across the Caribbean, the Gulf of Mexico, Florida and the Bahamas: for each month, the share of weeks from 2016–2024 when NOAA satellite data showed notable seaweed within about 20 km of shore. Download it as CSV or JSON and use it with credit (CC BY 4.0).

Download

sargassum-monthly-by-segment.csv: one row per stretch of coast (189 rows)
sargassum-monthly-by-region.csv: one row per Veabird beach region (43 rows)
sargassum-monthly.json: both tables with the metadata below

Columns jan to dec are shares from 0 to 1. Files are served with Access-Control-Allow-Origin: *, so you can fetch them from a browser. The weekly series behind them (53 weeks per stretch of coast) is at /data/sargassum/climatology.json.

segment_id,lat,lon,countries,regions,resorts,jan,feb,mar,apr,may,jun,jul,aug,sep,oct,nov,dec
30.5_-86.5,30.3864,-86.4602,US,fl_ph,8,0.093,0.024,0.077,0.232,0.107,0.032,0.072,0.131,0.14,0.234,0.196,0.142
30.5_-89,30.3851,-88.9607,US,al_ms,12,0.012,0.011,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.009,0.009,0.012
30.5_-87,30.343,-87.0626,US,fl_ph,4,0.083,0.058,0.024,0.062,0.035,0.009,0.016,0.053,0.081,0.107,0.154,0.089

What the numbers mean

Each value is the typical chance that, in a week of that month, the sea within about 20 km of that stretch of coast held more floating seaweed than in 4 out of 5 coast-weeks across the whole record. 0.05 means notable seaweed near shore in about 1 week in 20; 0.40 means about 2 weeks in 5. It is a history of how often the seaweed was there, not a forecast and not a measure of how much reached the sand.

A stretch of coast is a 0.5° grid cell (about 55 km) around the beaches Veabird forecasts; segment_id is the cell center as lat_lon and lat/lon the average position of its beaches. The region table gives the median over each region's beaches.

Method

Satellite data. NOAA AOML's Atlantic OceanWatch Alternative Floating Algae Index (AFAI) 7-day composites, the product behind the University of South Florida's Sargassum Watch System, sampled every week from 2016 in rings around each stretch of coast.
Nearshore signal. For each week, the highest of the 90th-percentile AFAI values in eight compass sectors within 0 to 20 km of the stretch of coast, using sectors where at least 15% of pixels were cloud-free. Weeks with no clear sector are left out.
Notable seaweed. A week counts when that signal is in the top fifth of all coast-weeks in 2016–2024 (the same event Veabird's sargassum model forecasts).
Seasonal climatology. The share of such weeks for each week of the year, pooled over ±2 weeks and shrunk slightly toward the overall rate where weeks are few, then averaged over the days of each month.

Limits: clouds hide the sea in some weeks; the satellite sees seaweed offshore, not on the beach; murky coastal water, river plumes and shallow banks can read as seaweed (Veabird's pages give no monthly level for 7 stretches where that is likely: Holguín, Izabal, Tela, Bocas del Toro; segments 21_-76, 21_-75.5, 16_-88.5, 16_-89, 16_-87.5, 9_-82.5, 9_-82); cleanup crews and barriers change what you see on a given beach. Years after 2024 are held out to test the forecast model and are not in this record.

Coverage and updates

Places: 189 stretches of coast in 25 countries and territories, covering 1,621 beaches and resorts (latitude 8.4° to 30.4°, longitude -97.8° to -59.6°). Mexico's Pacific coast and Hawaii are outside the satellite product.
Time: 2016–2024, by month of the year.
Updates: checked every week when Veabird's pages rebuild; the numbers change only when the model is retrained on a new year of satellite data.

Every region, every month

Percent of weeks with notable seaweed near shore on the median beach, 2016–2024. Click a column to sort.

Region	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Alabama & Mississippi Coast	1	1	1	1	1	1	1	1	1	1	1	1
Aruba, Bonaire & Curaçao	4	1	1	1	1	1	2	2	2	4	3	1
The Bahamas	9	12	7	6	3	5	6	4	3	8	9	7
Barbados	15	5	4	7	2	4	9	20	13	12	14	9
Belize	10	9	9	7	12	4	7	9	27	16	18	4
British Virgin Islands	12	3	7	5	6	8	5	9	17	11	15	18
Cancún & Isla Mujeres	44	45	50	53	57	51	63	65	62	45	42	31
Cayman Islands	1	3	3	1	1	2	6	6	4	3	2	4
Coastal Bend & South Texas	4	1	1	1	1	1	1	1	1	1	1	2
Colombia Caribbean Coast	6	3	2	1	11	14	20	20	22	11	17	17
Costa Maya & Bacalar	56	47	43	42	42	49	63	64	51	43	47	56
Costa Rica Caribbean	16	17	20	42	47	30	11	25	48	47	30	21
Cozumel	51	65	70	80	80	73	77	78	78	68	72	73
Cuba: Varadero & Havana	12	3	1	1	3	14	34	31	32	27	17	11
Cuba's Cays (Jardines del Rey, Santa María, Cayo Largo)	1	1	1	1	1	3	2	1	1	1	1	1
Dominican North Coast & Samaná	63	53	59	63	63	60	53	59	56	50	44	55
Florida Keys	1	1	1	1	2	3	2	5	7	8	9	7
Florida Panhandle	9	2	6	13	10	8	9	12	10	15	23	14
Guadeloupe, Martinique & Dominica	23	33	39	28	25	27	26	38	41	35	34	28
Guatemala Caribbean (Izabal)	42	61	68	71	67	59	35	59	80	60	52	43
Haiti	52	42	22	39	64	78	68	85	82	71	67	71
Holguín Coast (Guardalavaca)	64	72	72	68	68	81	75	73	87	83	67	70
Honduras & Bay Islands	9	5	3	5	8	4	2	6	6	1	3	3
Jamaica	30	26	28	38	42	45	43	49	44	36	31	32
Leeward Islands (Anguilla to Antigua)	24	22	7	5	9	4	7	20	20	19	19	13
Louisiana Coast	19	12	12	8	2	3	2	3	13	10	12	19
Nicaragua Caribbean (Corn Islands)	1	1	3	5	2	1	1	3	5	8	3	1
Panama Caribbean	17	21	19	30	21	10	11	27	31	26	23	20
Panama Pacific Beaches	23	25	15	7	15	15	3	20	23	22	30	33
Puerto Rico	1	2	9	13	10	13	17	14	8	6	8	4
Punta Cana & East Coast	58	57	63	72	77	77	70	69	71	66	73	69
Riviera Maya	51	65	70	80	80	73	77	78	78	68	72	73
San Andrés & Providencia	5	4	4	4	2	1	1	1	1	1	1	4
Santo Domingo & South Coast	51	31	32	42	56	63	52	58	66	67	58	58
Southwest Florida	3	1	1	1	3	4	4	4	6	4	7	4
Tampa Bay Beaches	3	3	6	4	7	9	9	9	17	23	15	12
Trinidad & Tobago	9	7	7	5	3	2	6	9	4	1	4	8
Turks & Caicos	1	4	1	3	1	1	1	3	3	4	4	5
U.S. Virgin Islands	12	17	9	3	5	4	3	6	9	7	21	13
Upper Texas Coast	6	11	5	2	1	1	1	1	5	8	5	4
Veracruz & Tamaulipas	1	1	2	5	7	14	20	25	23	11	7	2
Windward Islands (St. Lucia, SVG, Grenada)	19	15	14	23	11	8	21	29	25	15	18	18
Yucatán & Campeche Gulf Coast	4	1	1	1	2	4	8	11	7	3	1	1

Levels used on Veabird's pages (share of weeks): Very low under 10%, Low 10–24%, Moderate 25–44%, High 45–69%, Very high 70%+. Ranked Caribbean destinations by month: least seaweed by month.

License and credit

Free to use, share and adapt, including commercially, under Creative Commons Attribution 4.0 International (CC BY 4.0). Credit “Veabird (veabird.com), from NOAA AOML Atlantic OceanWatch AFAI satellite data (algorithm: University of South Florida Optical Oceanography Lab)” and link to this page.

The underlying satellite data are from NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML) Atlantic OceanWatch, using the Alternative Floating Algae Index developed by the University of South Florida Optical Oceanography Lab (Hu, 2009). NOAA and USF do not endorse this dataset.

Cite as

Veabird (2026). Caribbean sargassum: monthly nearshore record by stretch of coast, 2016–2024. https://veabird.com/datasets/sargassum/. Derived from NOAA AOML Atlantic OceanWatch AFAI 7-day composites (University of South Florida algorithm). License: CC BY 4.0.

This week's sargassum report: where seaweed is landing now
Least seaweed by month: Caribbean destinations ranked
Free JSON API and embeddable widgets
Questions or corrections: hello@veabird.com