Grève de Penn al Lann

Forecasts come from ~8 km resolution models: very local effects (a sheltering pier, a lagoon pass) are not captured.

The sea state is read as close to the beach as the model allows, without our having verified that this water is the water at the shore (indented coast, ria, head of a bay). Take it as an order of magnitude: what comes in from open sea may not reach this far.

Wave heights are significant heights: individual waves up to 2× this height still occur.

Four wave models are compared for this point: EWAM, GWAM, Météo-France WAM and ECMWF WAM.

Tide times derived from modelled sea level (± a few tens of minutes) — not official tide tables.

Missing data is shown as missing — never silently estimated.

Beach locations from OpenStreetMap — © OpenStreetMap contributors (ODbL).

Weather and marine data: Open-Meteo.com (CC BY 4.0), wave models from the Deutscher Wetterdienst (CC BY 4.0). Forecasts are not guarantees. · Data fetched at 15:26 UTC

Water clarity generated using E.U. Copernicus Marine Service Information.

Windows, comfort score and verdicts are computed by oswim from this data — modified values, not the institutes' raw figures.