Except for the south western province of Asir, Saudi Arabia has a desert climate with extremely high day-time temperatures and a sharp temperature drop at night.
Until the 1980s, Saudi Arabia had lakes at Layla Aflaj and deep waterholes at Al-Kharj, fed by huge underground aquifers, formed in prehistoric times and non-renewable. Al Kharj was a valuable source of drinking water in an barren terrain. In recent years, these aquifer have been drawn upon heavily, both for agricultural and domestic purposes, and no fresh water remain in the lakes or pits.
Saudi Arabia occupies about 80 percent of the Arabian peninsula, lying between latitudes 16° and 33° N, and longitudes 34° and 56° E.