Water temperature is an essential parameter in evaluating the composition and biological activity in a water body. The temperature of lakes, rivers, and oceans affects the health of plants and animals that live in and around these bodies of water. Increased water heat can contribute to the decline and migration of fish populations, the bleaching of coral, and an increase in toxic algae blooms.

Ocean water temperature provides fundamental information on the global climate system and aids in weather prediction and atmospheric model simulations. Climbing ocean temperatures due to global warming have drastic impacts on weather patterns, such as an increase in the number of storms that escalate into hurricanes. Higher water temperatures also contribute to sea level rise due to melting ice and thermal expansion.

NASA collects satellite and in-situ data about water temperature around the world, as well as related data such as water quality, salinity, and chemical composition. Some of these products are local to a specific region, while others survey the globe.