Oman and the United Arab Emirates lie in the hyper-arid zone of the Arabian Penninsula, and by nature are chronically water short. The Oman Mountain range that rises near the eastern coast with the Arabian Sea and the Indian Ocean plays a major role in defining the precipitaton regimes of the region. Surprisingly, despite the intense summer heat found throughout the region summer convective rainfall is a signficant fraction of the total annual preciptation, with less inter-annual variability. However, there is still uncertainitly regarding the role of summer convective rainfall in providing recharge of alluvial aquifers. A rain-gage based analysis is presented of seasonal and inter-annual rainfall patterns as well as observations of alluvial aquifer recharge. Issues related to the operation of recharge dams is presented in light of these findings.