Land Surface Temperature (LST) may be estimated using thermal infrared data as acquired by the Advanced Very High Resolution Radiometer (AVHRR) onboard the National Oceanic and Atmospheric Administration (NOAA) satellites. For LST to be estimated, algorithms based on the 'Split Window' method are applied, their performance depending greatly on the accurate definition of the precipitable water (PW) in the area of the satellite image. In this study, the precipitable water in the area of Greece as calculated from radiosonde data (00:00 UTC and 12:00 UTC) for a period of 29 years (1967-1995) for the Hellenikon Station (37° 54′ N, 23° 44′ E) is used to improve the performance of a split window algorithm for LST. The 'PW adjusted' algorithm is applied in a series of NOAA/AVHRR images in order to estimate LST for South and Central Greece. A case study is presented, where results are compared with in situ temperature measurements from surface stations of the National Meteorological Service to demonstrate very good agreement.