Rainfall is negligible, averaging 100 millimeters per year, confined to the winter months, and falling in brief, sometimes heavy storms that often flood the small ravines and the usually dry wadis.

The scarcity of rainfall and the limited underground water, most of which has such a high mineral content that it is unsuitable for drinking or irrigation, restricted the population and the extent of agricultural and industrial development the country could support until desalination projects began. Although water continues to be provided from underground sources, most is obtained by desalination of seawater.