Portugal · coast guide
Understanding the coast of Portugal
This guide explains the coast of Portugal on the Atlantic; calculations, observations and product limits remain distinct.
Read a local tide
Times and heights depend on the port, datum and station timezone. Hydrographic Institute tables distinguish mainland Portugal, the Azores and Madeira. A time for Lisbon does not describe an Azorean beach or a Madeiran inlet: port, time zone and datum are part of the prediction. Always keep the table’s source when comparing places. A value from another place cannot be carried to a nearby beach. Mareloa preserves the source and timestamp of its data but does not replace the national hydrographic reference.
Tidal range and coast
The Atlantic mainland coast, the archipelagos and their reference ports do not respond in the same way to the astronomical cycle. Range depends on the coast and is not a national label. Use the times and heights for the named port, and do not infer access to the sand from an isolated range. Tidal range is the vertical difference between low and high water. Bays, depth and coastal shape change it, so one astronomical cycle does not create the same range everywhere. Mareloa creates no national coefficient for Portugal and infers no access from one number.
Prediction, model and observation
Prediction, model and observation answer different questions. A periodic prediction does not automatically include wind, swell or pressure, while an observation applies to one station and moment. Compare each item with its provenance and do not fill an absence with a reassuring estimate. An astronomical prediction calculates a periodic component. A model adds assumptions; an observation is a measurement at a station and time. Wind, pressure, waves and geography can change actual level. These categories remain separate and missing evidence never becomes reassuring.
Plan a coast visit
Bathing-water quality, fishing rules, cliff access and signs are local matters. Check the responsible authority, notices on site and the marine forecast before visiting the mainland or islands. The guide does not replace those checks and is not a navigation tool. Use this guide to understand provenance, not to decide an activity. Restrictions, health notices, access and signage are local and can change. Consult the competent authority and on-site information; Mareloa is not a navigation tool.
Reviewed source
This page cites and links to this public reference; it does not reproduce its tables.
Reviewed 2026-09-11.