Each beach page shows its latest sargassum reading and its date, or says it has none yet. This page says where that reading comes from and what it can tell you.
Where the reading comes from
The reading comes from NOAA’s Sargassum Inundation Risk map, a satellite product that NOAA’s Atlantic Oceanographic and Meteorological Laboratory publishes each day with CoastWatch and the University of South Florida.
When the day’s map is late, we use the newest one from the five days before it. The date on a reading is the date of the map it came from.
One reading covers a whole coast
The map rates stretches of coastline on four steps: low, warning, medium and high. We sort the points it rates around Barbados to the nearest of five coasts (west, south, southeast, east and north) and keep the highest rating on each coast.
Low shows here as Clear, warning and medium as Moderate, and high as Heavy.
We send that coast’s satellite reading to every beach on the coast. A beach whose page is password-protected gets no new reading while it stays protected, and a beach whose update fails keeps its older reading until the next run reaches it. The coast cards on our home page show each coast’s satellite reading from the last five days, or none when there is no reading that recent.
The west coast cap
The west coast sits in the Caribbean lee and gets far less sargassum than the Atlantic side. Our settings currently cap the satellite reading for the west coast at Moderate, so when the map rates the west coast high, its satellite reading shows Moderate. The cap applies to the satellite reading only: a report from someone on a west coast beach shows the level they saw. A satellite reading at the cap says “capped at Moderate”, because the satellite may have rated that coast higher.
Reports from people on the beach
Anyone can send a report from a beach. Our team checks a visitor’s report before it counts, and a report from our own team counts straight away.
Under our current settings, a report from a person outranks the satellite reading for the same day. The newest date always wins, so the next day’s satellite reading takes over again.
A reading a person made is marked “Verified” with its date. A satellite reading is marked “Satellite reading for this coast” with its date. A reading we cannot trace to either is marked “Last reading”.
What a satellite reading cannot see
- It is a risk rating for the water off a coast. It does not count the weed on the sand at any one beach.
- It cannot tell one beach from another on the same coast.
- It judges each stretch of coast from 50 to 100 km of sea around it, which is wider than the island, so on many days all five coasts get the same rating.
- The map we use can be up to five days old on the day we read it. Once a satellite reading is more than five days old, the coast cards and beach cards stop showing it, and a beach page shows it without its status colour as its last reading, with its date.
If you are on a beach today, your report is the best reading we can show. Report today’s conditions.