Water vapor in the lowermost stratosphere has a pronounced seasonal cycle and hemispheric asymmetry. The Asian monsoon circulation is considered the main contributor to the higher water vapor amount in the northern Summer/Fall season. We examine the water vapor variability during Asian monsoon using the Microwave Limb Sounder observations of upper troposphere humidity (UTH) and stratospheric H2O. Signature of water vapor transport is compared with the potential vorticity distribution and other meteorological fields.