Data

Global sea-surface temperature against 1961–1990 (HadSST4)

Name: Global sea-surface temperature against 1961–1990 (HadSST4)
License: https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/

Global mean sea-surface temperature for each complete year since 1850, from ship and buoy measurements, as the difference from the 1961–1990 average, with a one-standard-deviation range.

Latest value

0.84°C

Global ocean, averaged over 5° grid boxes that have measurements (not interpolated), 2025. Version 4.2.0.0.

Global sea-surface temperature against 1961–1990 (HadSST4) (degrees Celsius)

176 values from 1850 to 2025. The shaded band is the uncertainty range the producer gives.

Show as a table

Global sea-surface temperature against 1961–1990 (HadSST4), every value
Period	Value (°C)	Range	Status
1850	−0.29	−0.40 to −0.18	final
1851	−0.18	−0.29 to −0.06	final
1852	−0.17	−0.27 to −0.06	final
1853	−0.20	−0.29 to −0.10	final
1854	−0.25	−0.34 to −0.17	final
1855	−0.23	−0.31 to −0.14	final
1856	−0.29	−0.37 to −0.21	final
1857	−0.41	−0.50 to −0.33	final
1858	−0.39	−0.48 to −0.30	final
1859	−0.27	−0.35 to −0.18	final
1860	−0.22	−0.32 to −0.13	final
1861	−0.35	−0.46 to −0.25	final
1862	−0.39	−0.49 to −0.28	final
1863	−0.32	−0.42 to −0.21	final
1864	−0.36	−0.46 to −0.26	final
1865	−0.20	−0.31 to −0.10	final
1866	−0.20	−0.30 to −0.09	final
1867	−0.19	−0.30 to −0.09	final
1868	−0.20	−0.32 to −0.09	final
1869	−0.27	−0.37 to −0.18	final
1870	−0.21	−0.30 to −0.13	final
1871	−0.22	−0.31 to −0.13	final
1872	−0.23	−0.32 to −0.15	final
1873	−0.28	−0.37 to −0.20	final
1874	−0.38	−0.46 to −0.30	final
1875	−0.23	−0.31 to −0.15	final
1876	−0.33	−0.42 to −0.25	final
1877	−0.01	−0.10 to 0.07	final
1878	0.01	−0.08 to 0.09	final
1879	−0.19	−0.27 to −0.11	final
1880	−0.19	−0.27 to −0.12	final
1881	−0.14	−0.22 to −0.06	final
1882	−0.20	−0.28 to −0.13	final
1883	−0.24	−0.31 to −0.17	final
1884	−0.34	−0.41 to −0.28	final
1885	−0.33	−0.40 to −0.26	final
1886	−0.34	−0.41 to −0.28	final
1887	−0.41	−0.48 to −0.35	final
1888	−0.24	−0.31 to −0.18	final
1889	−0.16	−0.23 to −0.09	final
1890	−0.43	−0.50 to −0.35	final
1891	−0.27	−0.34 to −0.19	final
1892	−0.41	−0.49 to −0.33	final
1893	−0.40	−0.48 to −0.32	final
1894	−0.43	−0.51 to −0.35	final
1895	−0.34	−0.42 to −0.26	final
1896	−0.14	−0.22 to −0.07	final
1897	−0.19	−0.26 to −0.12	final
1898	−0.42	−0.50 to −0.35	final
1899	−0.30	−0.38 to −0.22	final
1900	−0.22	−0.30 to −0.14	final
1901	−0.35	−0.43 to −0.27	final
1902	−0.44	−0.51 to −0.36	final
1903	−0.56	−0.63 to −0.48	final
1904	−0.59	−0.66 to −0.51	final
1905	−0.42	−0.50 to −0.35	final
1906	−0.37	−0.44 to −0.29	final
1907	−0.46	−0.53 to −0.39	final
1908	−0.56	−0.63 to −0.50	final
1909	−0.59	−0.65 to −0.52	final
1910	−0.58	−0.65 to −0.52	final
1911	−0.59	−0.65 to −0.52	final
1912	−0.45	−0.51 to −0.39	final
1913	−0.48	−0.54 to −0.43	final
1914	−0.34	−0.40 to −0.28	final
1915	−0.23	−0.29 to −0.16	final
1916	−0.41	−0.48 to −0.35	final
1917	−0.46	−0.54 to −0.38	final
1918	−0.41	−0.50 to −0.33	final
1919	−0.37	−0.45 to −0.29	final
1920	−0.29	−0.36 to −0.22	final
1921	−0.26	−0.33 to −0.19	final
1922	−0.35	−0.41 to −0.28	final
1923	−0.32	−0.38 to −0.26	final
1924	−0.31	−0.38 to −0.25	final
1925	−0.27	−0.33 to −0.21	final
1926	−0.15	−0.21 to −0.08	final
1927	−0.22	−0.28 to −0.16	final
1928	−0.25	−0.32 to −0.19	final
1929	−0.32	−0.38 to −0.26	final
1930	−0.17	−0.23 to −0.10	final
1931	−0.11	−0.18 to −0.05	final
1932	−0.19	−0.26 to −0.13	final
1933	−0.17	−0.24 to −0.11	final
1934	−0.12	−0.18 to −0.06	final
1935	−0.13	−0.19 to −0.07	final
1936	−0.10	−0.15 to −0.04	final
1937	0.05	−0.01 to 0.11	final
1938	−0.04	−0.10 to 0.02	final
1939	0.01	−0.05 to 0.08	final
1940	0.14	0.07 to 0.21	final
1941	0.02	−0.08 to 0.12	final
1942	−0.02	−0.13 to 0.10	final
1943	−0.03	−0.15 to 0.09	final
1944	0.12	0.00 to 0.23	final
1945	0.11	−0.01 to 0.23	final
1946	−0.10	−0.20 to 0.00	final
1947	−0.17	−0.27 to −0.07	final
1948	−0.16	−0.26 to −0.06	final
1949	−0.15	−0.22 to −0.07	final
1950	−0.16	−0.23 to −0.09	final
1951	−0.06	−0.13 to 0.01	final
1952	0.04	−0.03 to 0.11	final
1953	0.05	−0.01 to 0.12	final
1954	−0.14	−0.20 to −0.07	final
1955	−0.22	−0.28 to −0.15	final
1956	−0.23	−0.29 to −0.17	final
1957	−0.03	−0.09 to 0.03	final
1958	0.00	−0.06 to 0.05	final
1959	−0.06	−0.11 to −0.01	final
1960	−0.10	−0.15 to −0.05	final
1961	−0.04	−0.09 to 0.00	final
1962	−0.10	−0.14 to −0.05	final
1963	−0.04	−0.09 to 0.00	final
1964	−0.25	−0.29 to −0.21	final
1965	−0.21	−0.25 to −0.17	final
1966	−0.10	−0.14 to −0.05	final
1967	−0.16	−0.20 to −0.12	final
1968	−0.15	−0.19 to −0.12	final
1969	0.01	−0.03 to 0.05	final
1970	−0.10	−0.13 to −0.07	final
1971	−0.26	−0.29 to −0.23	final
1972	−0.02	−0.05 to 0.01	final
1973	0.01	−0.02 to 0.04	final
1974	−0.14	−0.17 to −0.11	final
1975	−0.15	−0.18 to −0.11	final
1976	−0.12	−0.16 to −0.09	final
1977	0.09	0.05 to 0.12	final
1978	0.03	0.00 to 0.06	final
1979	0.15	0.12 to 0.17	final
1980	0.14	0.11 to 0.17	final
1981	0.12	0.09 to 0.15	final
1982	0.10	0.06 to 0.13	final
1983	0.20	0.16 to 0.23	final
1984	0.06	0.03 to 0.10	final
1985	0.05	0.02 to 0.08	final
1986	0.08	0.05 to 0.11	final
1987	0.24	0.20 to 0.27	final
1988	0.21	0.18 to 0.24	final
1989	0.17	0.14 to 0.20	final
1990	0.30	0.26 to 0.33	final
1991	0.28	0.24 to 0.31	final
1992	0.18	0.15 to 0.22	final
1993	0.21	0.17 to 0.25	final
1994	0.25	0.21 to 0.29	final
1995	0.31	0.27 to 0.34	final
1996	0.25	0.21 to 0.28	final
1997	0.43	0.39 to 0.46	final
1998	0.51	0.48 to 0.55	final
1999	0.28	0.24 to 0.32	final
2000	0.28	0.25 to 0.32	final
2001	0.39	0.36 to 0.43	final
2002	0.44	0.40 to 0.47	final
2003	0.46	0.43 to 0.50	final
2004	0.44	0.41 to 0.47	final
2005	0.45	0.42 to 0.48	final
2006	0.43	0.40 to 0.46	final
2007	0.37	0.34 to 0.39	final
2008	0.34	0.31 to 0.37	final
2009	0.49	0.46 to 0.52	final
2010	0.49	0.47 to 0.52	final
2011	0.39	0.36 to 0.41	final
2012	0.46	0.43 to 0.49	final
2013	0.48	0.45 to 0.52	final
2014	0.58	0.55 to 0.62	final
2015	0.71	0.68 to 0.74	final
2016	0.73	0.70 to 0.76	final
2017	0.65	0.62 to 0.68	final
2018	0.62	0.59 to 0.64	final
2019	0.71	0.68 to 0.74	final
2020	0.70	0.67 to 0.73	final
2021	0.63	0.59 to 0.66	final
2022	0.68	0.65 to 0.71	final
2023	0.93	0.89 to 0.96	final
2024	0.95	0.92 to 0.98	final
2025	0.84	0.81 to 0.87	final

Calculated by Environment Dashboard from HadSST.4.2.0.0. HadSST.4.2.0.0 data were obtained from http://www.metoffice.gov.uk/hadobs/hadsst4 on 2026-10-05 and are © British Crown Copyright, Met Office 2025, provided under an Open Government Licence, https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Changes: range shown as the anomaly minus and plus the published total uncertainty (one standard deviation). Open Government Licence v3.0 (Crown copyright).

Where it comes from

Producer: Met Office Hadley Centre · HadSST.4 sea-surface temperature anomalies
Version: 4.2.0.0
File: https://www.metoffice.gov.uk/hadobs/hadsst4/data/data/HadSST.4.2.0.0_annual_GLOBE.csv
Fetched: 2026-10-05 (automatically), 14,097 bytes
Fingerprint: sha256 38dd997dc6716cdae019e41d37a5436178d07554a7d69287411904c14e67fa01ETag "3711-65b81f9231a40" · Last-Modified Tue, 15 Sep 2026 09:14:09 GMT
Copies: No Wayback copy recorded yet.Our copy of the exact file
Cite the producer: Kennedy, J. J., Rayner, N. A., Atkinson, C. P., & Killick, R. E., 2019. An Ensemble Data Set of Sea Surface Temperature Change from 1850: The Met Office Hadley Centre HadSST.4.0.0.0 Data Set. Journal of Geophysical Research: Atmospheres, 124. https://doi.org/10.1029/2018JD029867. Sandford, C., and Rayner, N., 2026. Addressing the World War 2 Warm Anomaly in HadSST.4.2.0.0. International Journal of Climatology. https://doi.org/10.1002/joc.70388.

Producer: Met Office Hadley Centre · HadSST.4 sea-surface temperature anomalies
Version: 4.2.0.0
File: https://www.metoffice.gov.uk/hadobs/hadsst4/data/data/HadSST.4.2.0.0_monthly_GLOBE.csv
Fetched: 2026-10-05 (automatically), 172,297 bytes
Fingerprint: sha256 07444a0e9be79dfe546f29d34e8dbbf561036e172b89eea45c3487c2b58dada6ETag "2a109-65b81f9231a40" · Last-Modified Tue, 15 Sep 2026 09:14:09 GMT
Copies: No Wayback copy recorded yet.Our copy of the exact file
Cite the producer: Kennedy, J. J., Rayner, N. A., Atkinson, C. P., & Killick, R. E., 2019. An Ensemble Data Set of Sea Surface Temperature Change from 1850: The Met Office Hadley Centre HadSST.4.0.0.0 Data Set. Journal of Geophysical Research: Atmospheres, 124. https://doi.org/10.1029/2018JD029867. Sandford, C., and Rayner, N., 2026. Addressing the World War 2 Warm Anomaly in HadSST.4.2.0.0. International Journal of Climatology. https://doi.org/10.1002/joc.70388.

What was done to it

Read the global annual series of HadSST.4.2.0.0 (sea-surface temperature anomaly in kelvin relative to 1961–1990, as published; a difference of 1 K equals 1 °C, so the values are unchanged). The file holds complete years, 1850 to 2025; each was confirmed to have all 12 months in the global monthly file.
Code: pipeline/src/envdash/transforms/temperature/hadsst4.py · code sha256 d556dbda6cbcbcbc… · inputs 38dd997dc671… 07444a0e9be7…
Lower and upper are the anomaly minus and plus the file's total_uncertainty, which the Product User Guide defines as the 1σ uncertainty combining uncorrelated measurement, sampling, correlated measurement, bias-correction and coverage uncertainties. The file's 95% bounds cover bias uncertainty only and are not used.
Code: pipeline/src/envdash/transforms/temperature/hadsst4.py · code sha256 d556dbda6cbcbcbc… · inputs 38dd997dc671… 07444a0e9be7…

What it covers

Geography: Global ocean, averaged over 5° grid boxes that have measurements (not interpolated)
Baseline: 1961–1990, the dataset's own baseline (as published)
Basis: In situ sea-surface temperature from ships and buoys, adjusted for changes in how it was measured.
Unit: degrees Celsius (°C)

Get the numbers

CSV JSON, with full provenance

Licence: Open Government Licence v3.0 (Crown copyright) (free to reuse with credit). Credit: Calculated by Environment Dashboard from HadSST.4.2.0.0. HadSST.4.2.0.0 data were obtained from http://www.metoffice.gov.uk/hadobs/hadsst4 on 2026-10-05 and are © British Crown Copyright, Met Office 2025, provided under an Open Government Licence, https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Changes: range shown as the anomaly minus and plus the published total uncertainty (one standard deviation).

How to cite

Kennedy, J. J., Rayner, N. A., Atkinson, C. P., & Killick, R. E., 2019. An Ensemble Data Set of Sea Surface Temperature Change from 1850: The Met Office Hadley Centre HadSST.4.0.0.0 Data Set. Journal of Geophysical Research: Atmospheres, 124. https://doi.org/10.1029/2018JD029867. Sandford, C., and Rayner, N., 2026. Addressing the World War 2 Warm Anomaly in HadSST.4.2.0.0. International Journal of Climatology. https://doi.org/10.1002/joc.70388. Via Environment Dashboard, https://environmentdashboard.org/data/sst/hadsst4/annual-1961-1990 (version 4.2.0.0, data accessed 2026-10-05).

Sources

HadSST.4 sea-surface temperature anomalies Report a problem with this number