About the sea surface temperature timeseries graphs

Analyses available

Sea Surface Temperature (SST) timeseries are available from 1900 for a number of regions around Australia and globally. These timeseries include ocean surface temperatures only and do not include any land surface temperatures.

SST timeseries are presented as anomalies or departures from the climatological average. This is because temperature anomalies tend to be more consistent throughout wide areas than absolute temperature values. SST timeseries anomalies relative to the 1961–1990 and 1991–2020 periods are presented.

The actual data values used to produce each graph are available via the "Raw dataset" link. The format for these data is:

<start year><start month><end year><end month> <mean temperature anomaly (°C)>

The "Sorted dataset" link provides the timeseries as a sorted list in order to place recent values in historical context.

Regions shown

Mean SST values are provided globally, for oceans form 60°S to 60°N, for a boxed region around Australia (from 4°S to 46°S and from 94°E to 174°E), as well as for six regions within this box:

  • the Northern Tropics (4°S–22°S, 94°E–174°E)
  • the Southern Region (30°S–46°S, 94°E–174°E)
  • the Southwest Region (22°S–46°S, 94°E–116°E)
  • the Northwest Region (4°S–22°S, 94°E–130°E)
  • the Coral Sea (4°S–26°S, 142°E–174°E)
  • the Tasman Sea (26°S–46°S, 150°E–174°E)

Values are also provided for the Great Barrier Reef (see below for details).

These regions are the same as those used to provide trend maps on these pages.

Regions around Australia used in sea surface temperature timeseries

Timeseries are determined globally and for the seven regions shown above

The above areas have been chosen for analysis since they are large enough to contain a meaningful climatology and not be influenced by data and interpolation errors. At the same time, these areas are small enough to provide a meaningful representation of regional climate influences around the Australian continent.

Great Barrier Reef

In addition to the larger boxed areas shown above, timeseries are also produced for the Great Barrier Reef. This is calculated from the average of seven grid points that are in or close to the Great Barrier Reef Marine Park. Only seven points can be used because the underlying data is on a relatively coarse grid, of 2° (about 220 km) resolution. This also means that small scale features may not be fully resolved.

Map of the Queensland coast showing the Great Barrier Reef and the seven grid points used for the Great Barrier Reef timeseries

The seven grid points used for the Great Barrier Reef timeseries

Data used

The SST timeseries are calculated using the NOAA Extended Reconstructed Sea Surface Temperature Version 6 (ERSSTv6) dataset, provided by the NOAA National Centers for Environmental Information (NCEI), USA. ERSSTv6 is a global monthly analysis of sea surface temperatures, extending from January 1850 to the present, on a 2° x 2° latitude-longitude grid.

ERSSTv6 incorporates observations from ships, drifting and moored buoys, and Argo profiling floats. Its input data include the International Comprehensive OceanAtmosphere Data Set (ICOADS) Release 3.0.2, Argo observations from the Argo Global Data Assembly Centre, and sea-ice concentration data from HadISST2 for 1850‐2015 and NCEP from 2016 onwards. Very recent observations have not been subjected to the same degree of quality control as past data. ERSSTv6 does not include any satellite data, so recent SSTs can be better compared with historical periods.

ERSSTv6 introduces several methodological improvements compared with ERSSTv5. These include an artificial neural network (ANN) interpolation method to improve the reconstruction of sea surface temperatures and their spatial and temporal variability, a nearest-neighbour check in the quality control of ship observations, and a large-scale filter applied to SST super-observations. An updated algorithm is also used to estimate sea surface temperatures in ice-covered regions.

The transition from ERSSTv5 to ERSSTv6 results in some changes to historical SST values and to calculated trends and temperature extremes consequently. These changes reflect improvements in the reconstruction methodology and should be considered when comparing the updated timeseries with previously published values or analyses based on ERSSTv5.


Further information

The ERSSTv6 dataset is publicly available from the NOAA NCEI data archive.

Huang, B., X. Yin, T. Boyer, C. Liu, M. Menne, Y. D. Rao, T. Smith, R. Vose and H.-M. Zhang, 2025: Extended Reconstructed Sea Surface Temperature Version 6 (ERSSTv6): Part I. An Artificial Neural Network Approach. Journal of Climate, 38, 11051121. doi.org/10.1175/JCLI-D-23-0707.1

Huang, B., X. Yin, T. Boyer, C. Liu, M. Menne, Y. D. Rao, T. Smith, R. Vose and H.-M. Zhang, 2025: Extended Reconstructed Sea Surface Temperature Version 6 (ERSSTv6): Part II. Upgrades on Quality Control and Large-scale Filter. Journal of Climate, 38, 11231136. doi.org/10.1175/JCLI-D-24-0185.1

Huang, B., P.W. Thorne, V.F. Banzon, T. Boyer, G. Chepurin, J. Lawrimore, M.J. Menne, T.M. Smith, R.S. Vose and H.-M. Zhang, 2017: Extended Reconstructed Sea Surface Temperature version 5 (ERSST.v5): Upgrades, validations and intercomparisons. Journal of Climate doi:10.1175/JCLI-D-16-0836.1

Great Barrier Reef features and park boundary spatial data provided by the Spatial Data Centre of the Great Barrier Reef Marine Park Authority. For more information or further spatial data, contact gis@gbrmpa.gov.au.

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