How sea-surface temperature data actually works
Satellites, buoys, and the model blends behind every number on SwimTemperature.
When a website shows you a sea temperature for a beach, that number almost never comes from someone standing in the water with a thermometer. It comes from a model that blends three layers of measurement.
Satellites measure the skin
Polar-orbiting satellites read the thermal infrared emission from the very top millimetre of the ocean. They cover the whole planet every few hours but miss the layer that matters to a swimmer — the top metre or two.
Buoys, Argo floats and ships measure depth
Anchored buoys and the global Argo float fleet measure temperature down through the water column. They are sparse but accurate.
Models fuse it together
Operational ocean models (Copernicus Marine, NOAA RTOFS) ingest both data streams and produce a gridded best-estimate. SwimTemperature pulls Open-Meteo's marine forecast, which blends these sources.