Met Office Hadley Centre
HadSST.4 sea-surface temperature anomalies
Monthly and annual sea-surface temperature anomalies from January 1850, from ship and buoy measurements (ICOADS, Met Office GTS ship data and Copernicus Marine drifting buoys) adjusted for changes in how SST was measured. Not interpolated. Anomalies are in kelvin (equal to degrees Celsius) relative to 1961–1990, with uncertainty split into measurement, sampling, bias and coverage parts. The global annual file holds complete years only (to 2025 on 2026-10-04).
Numbers published from it
Licence and credit
- What the terms say
“HadSST.4.2.0.0 is subject to Crown copyright protection and is provided under the Open Government Licence v3.”
From the producer's terms, checked 2026-10-04; re-checked automatically every week.
- Credit we give
- HadSST.{version} data were obtained from http://www.metoffice.gov.uk/hadobs/hadsst4 on {date_accessed} and are © British Crown Copyright, Met Office {year}, provided under an Open Government Licence, https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/
- Copy of the raw file
- Allowed: we keep a public copy of every version we use.
- Cite as
- 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.
Files
Global annual SST anomaly from 1850, K relative to 1961–1990, with total, uncorrelated, correlated, bias and coverage uncertainties (1σ) and the 95% bias-uncertainty range. Complete years only.
https://www.metoffice.gov.uk/hadobs/hadsst4/data/data/HadSST.4.2.0.0_annual_GLOBE.csvGlobal monthly SST anomaly from January 1850, K relative to 1961–1990, with the same uncertainty columns. Runs to August 2026 on 2026-10-04.
https://www.metoffice.gov.uk/hadobs/hadsst4/data/data/HadSST.4.2.0.0_monthly_GLOBE.csv
Status
- Programme
- Updated monthly. UK government (Met Office) dataset, not exposed to US federal cuts, though its main input (ICOADS) is maintained by NOAA and partners. The version is part of each file's URL, so a new version means a registry edit.
- Updates
- Monthly; a new minor version about once a year
- Last check
- Unchanged since the last fetch (2026-10-05T11:03:20Z)
- Independent sources measuring the same thing
- NOAA Daily Optimum Interpolation Sea Surface Temperature (OISST), version 2.1