Sargassum season in Miami, month by month

First: this is not a fixed calendar

Sargassum has a season, but it does not keep a schedule. Some years bring a lot and some almost none, and within the same month clean weeks can alternate with difficult ones. This guide describes the general pattern seen in South Florida. To decide whether to go today, what matters is your beach's level right now and the forecast for the next few days.

Winter: December to February

These are usually the quietest months. Little sargassum arrives and beaches often stay clean for days in a row. Cold fronts change the wind often and sometimes push a little toward the coast, but it rarely lasts.

Spring: March to May

This is when it starts to show in heavy years. The first mats appear on some beaches, especially with east or southeast winds. April and May can be very different from one year to the next: check the forecast before planning a whole day.

Summer: June to August

In general these are the months with the most sargassum in the Atlantic and the ones that leave the most on the sand. Not every day and not every beach: wind and the shape of the coast are still in charge. This is when comparing nearby beaches pays off most, because the difference between two of them can be large.

Fall: September to November

The amount usually tapers off little by little. September can still bring heavy days, and storms and wind shifts stir things up. By November things usually calm down again.

How to use this guide

• To plan a trip, winter and late fall are usually safer bets, but not guaranteed ones.
• To decide today, check the beach's level and its forecast. Today and the next three days are a forecast; days four to six show only a trend.
• If your beach looks bad, there is almost always another one nearby in better shape. The beach list sorts them by area.

The season tells you what is likely. Today's index tells you what is there.