This paper examines the trends in the Southern Annular Mode (SAM), a significant mode of atmospheric variability in the Southern Hemisphere, using station data from the Southern Hemisphere to establish a "true" benchmark. The SAM is defined as the difference in zonal mean sea level pressure (MSLP) between 40°S and 65°S, with a positive phase indicating a strengthening of the circumpolar vortex and intensification of westerlies. Previous studies have reported a significant trend toward the positive phase of the SAM using the NCEP-NCAR reanalysis (NNR) data, which is known to have spurious negative trends in high-latitude pressure. The study uses six stations to calculate a proxy zonal mean MSLP at both 40° and 65°S during 1958–2000, showing a statistically significant increase in the difference between these latitudes, most pronounced since the mid-1970s. However, the trends in the NNR data are exaggerated by factors of 3 and 2 for the MSLP difference and the SAM itself, respectively. The ERA-4 reanalysis, which includes part of the new NNR reanalysis, is found to provide a more reliable estimate of high-latitude atmospheric circulation variability, with significant trends at least as far back as 1973. The study concludes that the true trend in the SAM is less pronounced than previously reported, and that the NNR data have introduced significant errors in the interpretation of past changes in the SAM.This paper examines the trends in the Southern Annular Mode (SAM), a significant mode of atmospheric variability in the Southern Hemisphere, using station data from the Southern Hemisphere to establish a "true" benchmark. The SAM is defined as the difference in zonal mean sea level pressure (MSLP) between 40°S and 65°S, with a positive phase indicating a strengthening of the circumpolar vortex and intensification of westerlies. Previous studies have reported a significant trend toward the positive phase of the SAM using the NCEP-NCAR reanalysis (NNR) data, which is known to have spurious negative trends in high-latitude pressure. The study uses six stations to calculate a proxy zonal mean MSLP at both 40° and 65°S during 1958–2000, showing a statistically significant increase in the difference between these latitudes, most pronounced since the mid-1970s. However, the trends in the NNR data are exaggerated by factors of 3 and 2 for the MSLP difference and the SAM itself, respectively. The ERA-4 reanalysis, which includes part of the new NNR reanalysis, is found to provide a more reliable estimate of high-latitude atmospheric circulation variability, with significant trends at least as far back as 1973. The study concludes that the true trend in the SAM is less pronounced than previously reported, and that the NNR data have introduced significant errors in the interpretation of past changes in the SAM.