Upper troposphere (UT) humidity records are crucial for climate studies. Pseudo-monthly averaging limited just to nighttime measurement is applied to maximize temporal representativeness and enhance the lidar signal, providing WVMR profiles up to 16 km. This study evaluates 11 years (2013–2023) of water vapor mixing ratio (WVMR) profiles from a UV Raman lidar (Lid1200) at Réunion Island against MLS-Aura satellite retrieval, ERA5 reanalysis, and GRUAN-processed M10 radiosondes. The results show a systematic dry shift in MLS of up to 30% above 12 km, particularly during the wet season. Lidar exhibits a slight downward shift in WVMR, around 5% lower than ERA5 throughout the UT, with the largest deviations present above 14 km and greater variability during the wet season, Lidar calibration-related challenges during the dry season result in drier-than-ERA5 WVMR profiles (up to 10%). Additionally, comparisons with GRUAN-processed radiosonde reveal a substantial dry shift relative to the lidar, exceeding 30% above 12 km. We investigate the GNSS-based lidar calibration effect by applying an alternative calibration method. This produces higher WVMR values, revealing an ERA5 dry shift relative to lidar, increasing with altitude at the UT up to 25%. These measurements complement the global effort in monitoring and validating the tropical and subtropical upper tropospheric humidity.