Ice Shelf Water (ISW) characteristics are investigated using data from moored instruments in the southern Weddell Sea. Most attention is given to the temperature data, but additional current, salinity and oxygen data are included to increase the credibility of the observations. The main data set is from a mooring site, named S2, located at the Filchner Sill. Year-long time series exists in 1977, 1985, 1987, 2003 and 2010 making this one of the longest time series in Antarctic waters. To supplement the S2 series, data are included from the FR1 mooring, southeast of the S2 position. Both seasonal and interannual variability are observed in the ISW at the Filchner Sill. Any long-term trend in the ISW is not found. A new explanation of the seasonal signal is presented, suggesting that the signal is a result from the forcing in front of the Ronne Ice Shelf. Changes in atmospheric forcing, the occurrence of polynyas and grounded icebergs are suggested to be the reason for interannual variations. Master i Meteorologi og oseanografi MAMN-GEOF GEOF399