The UAE has an arid climate with less than 100mm per year of rainfall, a high evaporation rate of surface water and a low groundwater recharge rate. Although rainfall in the UAE has been fluctuating over the last few decades in winter season, most of that occurs in the December to March period. During the summer months, the prevailing Indian Monsoon drought effect leads to a build-up of cumulus clouds especially along the mountainous terrain in the eastern UAE.[8]