🌊 Sea conditions
--°C
Detecting your location…
The temperature of the ocean surface at your location — vital for swimming, surfing, fishing, diving and marine forecasting.
Sea surface temperature (SST) is the temperature of the topmost layer of the ocean, and it shapes everything from your comfort in the water to the behaviour of storms and marine life. This page shows the current sea surface temperature at your chosen coastal location, alongside wave height, period and direction, drawn from a marine forecast model. Note that open-ocean and coastal points return data; locations well inland will not.
The ocean surface is warmed by sunlight and cooled by evaporation, by mixing with deeper water, and by contact with the air. Because water has a very high heat capacity, the sea warms and cools far more slowly than land — which is why coastal climates are milder and why the sea is often warmest in late summer, weeks after the longest day.
Ocean currents move enormous amounts of heat around the planet. Warm currents like the Gulf Stream carry tropical heat poleward, keeping north-western Europe far milder than its latitude would suggest. In some regions, winds push surface water away from the coast and cold, nutrient-rich water rises from below in a process called upwelling — this is why some coastlines have surprisingly cold, but very productive, seas.
A warm sea surface evaporates more water into the air, feeding clouds and rain. Tropical cyclones draw their energy directly from warm water and generally need a surface temperature above about 26.5°C to form and intensify. On smaller scales, the contrast between sea and land temperature drives sea breezes that shape coastal weather every day.
Sea surface temperature is measured by satellites that sense infrared and microwave radiation from the surface, by drifting and moored buoys, and by ships. These sources are combined into gridded analyses and forecasts. The wave data shown here — height, period and direction — comes from a model that simulates how wind transfers energy into the sea surface.
Water has a very high heat capacity and warms slowly, so it lags weeks behind the air. The sea is often coldest in late winter and warmest in late summer, well after the air has peaked.
Most people find water above about 20°C comfortable, and above 24°C very pleasant. Below 16°C feels cold to most swimmers and a wetsuit is recommended.
Sea surface temperature only exists over water. The marine model returns values for coastal and open-ocean points, so a location well inland will correctly show no reading.
Tropical cyclones draw energy from warm water and typically need a surface temperature above about 26.5°C. Warmer seas can fuel stronger, wetter storms.