Weather Explainers

Weather Words: Sea Surface Temperatures

Sea surface temperatures are vital measurements that indicate the warmth of the ocean's top layer, influencing weather patterns, climate, and marine ecosystems.

It may sparkle in the sun, but the ocean's surface is a dynamic thermometer for our planet. The sea surface temperature (SST) is measured by satellites and buoys in the ocean, to give the most accurate reading of the temperature on the ocean’s surface. When we say “sea surface” temperature, that’s referring to the temperature at the top - few millimeters, to a few centimeters below the surface. Once you go deeper into the ocean, the water temperature drops.

Sea surface temperatures across the globe can vary tremendously. SSTs near the equator can run as high as 85 degrees Fahrenheit, while temperatures can drop into the upper 20s near the poles. Some regions have pretty consistent temperatures, while other areas can see huge temperature swings in water temperatures depending on the season and how much cloud cover is present.

This image is an example of how sea surface temperatures are depicted. The warmer ocean temperatures are near the equator and cooler temperatures are near the poles.
(NASA)

Changes in SST can have significant impacts on weather patterns, ocean currents and marine ecosystems. For instance, warmer sea surface temperatures can lead to increased evaporation, which contributes to more intense and frequent storms. This is particularly evident in the tropics, where warm water fuels tropical systems, such as hurricanes. Studies have shown that more evaporation leads to stronger and rainier tropical systems that can dump unprecedented amounts of rainfall from a single storm.

Monitoring sea surface temperatures is vital for understanding global climate phenomena like El Niño and La Niña. El Niño, characterized by warmer SSTs in the central and eastern equatorial Pacific Ocean, can lead to widespread weather disruptions, including heavy rainfall and droughts across different regions. In contrast, La Niña, marked by cooler SSTs, typically brings opposite effects, such as increased hurricane activity in the Atlantic and drier conditions in the southeastern U.S.

SST also plays a significant role in marine ecosystems. Warmer ocean temperatures can lead to coral bleaching, disrupting marine habitats and affecting the fishing industry. Additionally, changes in SST can alter the distribution of fish species, impacting local economies reliant on fishing.

By tracking SST changes, researchers can better predict extreme weather events and their potential impacts on communities and ecosystems.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.

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