Monthly SST Anomaly: global

Monthly SST Anomaly: global

Is sea surface temperature warmer or cooler than usual?

Colors on this map show where and by how much monthly sea surface temperature differed from its 1981 to 2010 average. Red and orange areas were warmer than average, and blue areas were cooler than average. The darker the color, the larger the difference from the long-term average. White and very light areas were near their three-decade average.

Where do these measurements come from?

These monthly measurements are from NOAA’s Optimum Interpolation Sea Surface Temperature (OISST). The observations are from multiple sources: satellites, ships, and buoys. Scientists combine data from the different sources, and data visualizers plot them on a regular grid that spans the globe.

What do the colors mean? 

Shades of blue show locations where sea surface temperature was cooler than its long-term average from 1981 to 2010. Locations shown in shades of orange and red are where the sea’s surface was warmer than the long-term average. The darker the shade of red or blue, the larger the difference from the long-term average or “usual” sea surface temperature. Locations that are white or very light show where sea surface temperature was the same as or very close to its long-term average.

Why do these data matter? 

Water covers more than 70% of our planet's surface, so gathering data on ocean temperatures gives us a better picture of global temperatures. Tracking the temperature of the sea’s surface helps scientists understand how much heat energy is in the ocean and how it changes over time. Sea surface temperatures can have dramatic impacts on weather, including weather patterns such as El Niño-Southern Oscillation (ENSO) that travel hundreds of miles inland. Sea surface temperatures also play a significant role in the extent and thickness of Arctic and Antarctic sea ice, which serve as our planet’s built-in air-conditioning system. And sea surface temperatures have significant effects on marine life. The upwelling of cold water, for instance, provides nutrients to phytoplankton, the base of the marine food chain. In contrast, warm ocean surface waters deprive phytoplankton of nutrients, sometimes with devastating effects up the chain.

How did you produce these snapshots? 

Data Snapshots are derivatives of existing data products: to meet the needs of a broad audience, we present the source data in a simplified visual style. NOAA's Environmental Visualization Laboratory (NNVL) produces the Sea Surface Temperature Anomaly files. To produce our images, we run a set of scripts that access the source files, re-project them into a Hammer-Aitoff projection, and output them in a range of sizes.