Aswan extremity of Egypt, the river flows for more than without bar or cataract. The voyage from Aswan to Alexandria usually took 21 to 28 days in favourable weather. Aswan has a hot desert climate (Köppen climate classification "BWh") like the rest of Egypt. Aswan and Luxor have the hottest summer days of any city in Egypt. Aswan is one of the hottest, sunniest and driest cities in the world. Average high temperatures are consistently above during summer (June, July, August and also September) while average low temperatures remain above . Summers are long, prolonged and extremely hot. Average high temperatures
Aswan Low Dam in the lower Nile. The dam, originally limited in height by conservation concerns, worked as designed, but provided inadequate storage capacity for planned development and was raised twice, between 1907 and 1912 and again in 1929–1933. These heightenings still did not meet irrigation demands and in 1946 it was nearly over-topped in an effort to maximize pool elevation. This led to the investigation and construction of the Aswan High Dam upstream. The earliest recorded attempt to build a dam near Aswan was in the 11th century, when the Arab polymath and engineer Ibn al-Haytham (known as "Alhazen" in the West)