Atmospheric moisture transport is a key component of the hydrological cycle. Its stable isotopic composition (518O and 5D) and temporal variability are good tracers for understanding complex meteorological phenomena and their history at different time scales. In this study, we analyse measurement data on the isotopic composition of ambient atmospheric water vapor between July 2017 and December 2019, from Ahmedabad, a semi-arid location in western India. Seasonal to annual scale variabilities in rainfall are considerable, with 2019 having the highest rainfall, followed by 2017 and 2018. The number of rainy days varied significantly with 51 days being in 2017, 41 days in 2018 and 75 days in 2019. At inter-seasonal to annual timescales, notable variability is observed in the isotopic composition. During the monsoon season, rainfall occurrence primarily influenced the isotopic composition, whereas during the non-monsoon period, temperature and atmospheric moisture content played a dominant role. Strong temporal variation observed in the isotopic composition of the ambient atmospheric water vapor ranges from-2 %o to-27 %o and from-28 %o to-206 %o for 518O and 5D, respectively. A coherent correlation between 518O-5D is evident during the southwest monsoon and post-monsoon periods, with relatively weaker during the winter monsoon seasons, and insignificant during the pre-monsoon period. Intraseasonal 518O-5D correlations show variable levels, with in general a gradual decline in the slope values considering the southwest monsoon, the post-monsoon, and the winter monsoon periods; this seems to be associated with the changing moisture sources and fractionation process. Significant fluctuations in d-excess values are observed during the study period (ranges from-49 %o to 103 %o), largely driven by the moisture content of the surrounding air and strongly anti-correlated with 518O. Backward trajectory analysis indicates that elevated humidity levels during the late part of the pre-monsoon and monsoon are associated with moisture transport from the Arabian Sea, whereas during the low-humidity periods (winter monsoon) moisture sources are significantly influenced by the kinetic fractionation.