Sea surface temperature (SST) is the temperature of the top few metres of the ocean. It influences weather (e.g. tropical storms, coastal fog), marine ecosystems, and the global climate system. SST varies with latitude, season, currents, and local factors such as upwelling and river outflow. Satellites and in-situ instruments (buoys, ships) provide the observations used to produce global SST analyses and forecasts.

Oceans warm and cool more slowly than land, so coastal water temperature lags behind air temperature by weeks. Upwelling—cold deep water rising near coasts—can keep surface temperatures low even in summer. Regional differences are large: polar waters can be near freezing while tropical seas often exceed 28 °C. The values here are model-based estimates at your chosen location and are useful for trend and planning, not as a substitute for local measurements.

SST is measured by satellites (infrared and microwave), drifting and moored buoys, and ships. Operational centres such as NOAA and Copernicus combine these into gridded analyses. The data on this page is from the Open-Meteo Marine API, which uses a global ocean model and is updated regularly. For swimming and marine activities, always consider local conditions and official safety advice.

Did you know? In the open ocean, surface water can stay liquid a degree or two below 0 °C where salinity lowers the freezing point. The warmest sea surface temperatures are in enclosed or shallow tropical waters and can exceed 30 °C.