Most of Egypt's rain falls in the winter months. South of Cairo, rainfall averages only around  per year and at intervals of many years. On a very thin strip of the northern coast the rainfall can be as high as , mostly between October and March. Snow falls on Sinai's mountains and some of the north coastal cities such as Damietta, Baltim and Sidi Barrani, and rarely in Alexandria. A very small amount of snow fell on Cairo on 13 December 2013, the first time in many decades. Frost is also known in mid-Sinai and mid-Egypt. Egypt is the driest and the sunniest country in the world, and most of its land surface is desert.