What time of day usually has the least sargassum?

The beach changes during the day

Sargassum does not arrive all at once, and it does not sit still. Wind, tides and currents shift during the day, and the mats shift with them. That is why a beach can be clean at nine in the morning and have a band of seaweed by four in the afternoon, or the other way round. No single hour is always the best, but there are some patterns.

Wind matters most

In South Florida a sea breeze often picks up in the afternoon, blowing from the ocean toward the coast. That wind pushes any sargassum floating nearby onto the shore. So on many summer days, the morning tends to be cleaner than the afternoon. When the wind blows from land out to sea, the opposite happens: sargassum tends to drift away.

Tides leave their mark

At high tide the water reaches farther up the sand and leaves sargassum in a line. When the tide goes out, that line is left high and dry. If you arrive at low tide after a high tide with a lot of sargassum, you will see the band on the sand even if the water is cleaner.

Beach cleaning

Some Miami beaches have sargassum removed from the sand from time to time, mostly in the busiest areas. When and where that happens depends on each city or county, so our index does not assume it: we measure what is there, not what will be cleaned.

How to pick your time with our data

• Read the line of the day. When the forecast sees it coming, the beach page says so with lines such as "Go early: sargassum arrives later" or "Clean until…" followed by a time.
• Check the wind. Each beach page shows the current wind: if it is blowing hard off the sea, more sargassum is likely to arrive.
• Check how old the data is. The level always shows when it was last updated. A reading from twenty minutes ago is worth more than one from yesterday.
• Read today's reports. People on the sand see things the satellite cannot.

In short

If you have to choose with nothing else to go on, go early. If you have our data, even better: the current level, the wind and today's reports tell you more than any rule of thumb.