The Astan-Roscoff time-series data characterize the temperature and salinity of the Western English Channel. Between 1952 and 1982 the sampling station was located to the north-west of Batz Island. Since 1983, the sampling station is located at the current SOMLIT-Astan site (north-east of Batz Island). Monthly measurements have been undertaken during the 1952-1982 period, bi-monthly measurements have been undertaken since 1983 by Station Biologique de Roscoff/Sorbonne Université/CNRS. Since 1997, this station has been part of the French coastal environment monitoring network SOMLIT (https://www.somlit.fr/), accredited by the CNRS as a national Earth Science Observatory (Service National d’Observation: SNO), aiming at assessing their long-term evolution including both natural and anthropogenic forcings. Samples were collected with a Niskin bottle at high tide slack during neap tides at 2m-depth and at 60m-depth for the 1983-1999 period. Until 1970 the exact date of sampling is unknown, hence in the data set, the 1st of the month is present. Water samples where analysed for Salinity with a Salinometer Guidline Autocal and Temperature was measured during sampling with a reversing mercury thermometer (Richet and Wiese). Starting in 2000, this time series has been integrated in the SOMLIT ASTAN time-series, which is part of the SOMLIT National Observation Service.