The south coastal area of Iran, being adjacent to the humidity of the Persian Gulf and Oman Sea in addition to its high temperature and its high capacity for absorbing humidity, has a great potential for water harvesting from fog and air humidity. In this research, data have been collected from 10 synoptic stations adjacent to the Persian Gulf and Oman Sea, in order to investigate water harvesting from fog and air humidity. The data used in this study included hourly dry and wet temperature, relative humidity, wind direction and velocity and dew point temperature. By the use of these data, various parameters such as atmospheric water vapour pressure, saturated vapour pressure and the absolute humidity of the atmosphere were estimated. Finally, according to the investigations carried out in this study, it was clear that the cited regions had the potential to harvest fog water for 160–360 days. This is whilst the average number of foggy days in the region is 41 maximally. In addition the annual mean water harvested through this technique varies between 6.7 l m‾2 day‾1 at Abadan station and 156 l m‾2 day‾1 at Chabahar station. It is worth noting that the maximum amount of water harvested from the stations near the coastal areas occurs during the summer while at stations far from the coastal areas this happens during the winter. Copyright © 2013 John Wiley & Sons, Ltd.