Fetching this spot's conditions…
Tip of the moment
Fetching this spot's conditions…
Tip of the moment
Saint-Derrien · Bretagne
Today's take
Window: 10:00–19:00, with caution — read the safety panel before you go.
Water temperature
16.4 °C
Verdict
Glassy
1 reading unavailable
When to go
Good from 10:00 to 19:00.
Pin colours:swimmablecautionnot advisedconditions not loaded yet
Forecasts come from ~8 km resolution models: very local effects (a sheltering pier, a lagoon pass) are not captured.
Sea-state data comes from a marine model cell about 21.0 km from this point — local nearshore conditions can differ.
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.
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 03:27 UTC
Windows, comfort score and verdicts are computed by oswim from this data — modified values, not the institutes' raw figures.
min 1 · max 8 km/h · south-west sector · gusts 14 km/h
Post-rain pollution · 0 – 0.1 mm over 24 h
When it rains hard, runoff from roads and fields and sewer overflows carry bacteria out to sea. Nothing significant has fallen in the last 24 hours.
Official sampling is weekly at best; between two samples, recent rain is the recognized warning signal (EEA)
Jellyfish: no recent info. If you're there, tell us what you see — even “none” helps the next swimmer.
Water quality · Excellent · 2025 season
Computed from the samples of the last four bathing seasons. It says what the water here has been, not what it is today: after heavy rain, even an excellent beach degrades for a day or two.
Health authority classification (EU directive 2006/7/EC), published once per bathing season
Not assessed for this spot: Offshore wind.
In all cases: bright swim cap and tow float so boats can see you.
Consolidated ladder: World Aquatics / World Triathlon / FFTri rules + manufacturer thermal guides