Geography
Area: 125,000 sq. km. (48,000 sq. mi.); about the size of Pennsylvania.
Cities: Capital--Asmara (est. pop. 435,000). Other cities--Keren (57,000); Assab (28,000); Massawa (25,000); Afabet (25,000); Tessenie (25,000); Mendefera (25,000); Dekemhare (20,000); Adekeieh (15,000); Barentu (15,000); Ghinda (15,000).
Terrain: Central highlands straddle escarpment associated with Rift Valley, dry coastal plains, and western lowlands.
Climate: Temperate in the highlands; hot in the lowlands.

Eritrea Geography
Eritrea is located in the Horn of Africa and is bordered on the northeast and east by the Red Sea, on the west and northwest by Sudan, on the south by Ethiopia, and on the southeast by Djibouti. The country has a high central plateau that varies from 1,800 to 3,000 meters (6,000-10,000 ft.) above sea level. A coastal plain, western lowlands, and some 300 islands comprise the remainder of Eritrea's land mass. Eritrea has no year-round rivers.

The climate is temperate in the mountains and hot in the lowlands. Asmara, the capital, is about 2,300 meters (7,500 ft.) above sea level. Maximum temperature is 26o C (80o F). The weather is usually sunny and dry, with the short or belg rains occurring February-April and the big or meher rains beginning in late June and ending in mid-September.
source: http://www.state.gov