How to read tides

What a tide is

The tide is the regular rise and fall of sea level, caused mainly by the pull of the Moon and, to a lesser degree, the Sun.

High tide and low tide

• High tide: the moment the sea reaches its highest level.
• Low tide: the moment of lowest level.
• On most of the Argentine coast there are two high tides and two low tides a day, about 6 hours apart. The times shift by roughly an hour each day.

Tidal range: how much it rises and falls

The tidal range is the height difference between a high tide and the next low tide. It varies a lot by place: on some beaches of Buenos Aires province it is moderate, while in Patagonia it can reach several meters, so at the same hour a beach can look completely different.

Spring tides and neap tides

• Spring tides: around the new moon and full moon, tides are stronger: higher highs and lower lows.
• Neap tides: around the first and last quarter, tides are gentler.
• That is why the moon phase helps anticipate how much the water will move.

Wind and pressure matter too

Tide tables are computed from astronomy, but the real level can change with wind and atmospheric pressure. A steady onshore wind can push the level higher than predicted, and strong southeasterly winds (the “sudestada”) are known for raising the Río de la Plata. Many anglers also watch pressure changes, which often go along with fish behavior.

Estimated tides vs. official tides

The tides shown on this site are model estimates and can differ from what happens on the coast, especially in estuaries, rivers, harbors and bays. Official tides in Argentina are those published by the Servicio de Hidrografía Naval (hidro.gob.ar). For navigation, also check the notices of the Argentine Naval Prefecture.