Climate
Jordan can be classified as a semi-desert area. Only the highlands, with a width of around (30 km) and a length of some (300 km), enjoy a Mediterranean type climate. Temperatures in the Jordan Valley, Wadi Araba and Aqaba can rise in summer to 45°C with an annual average of 24°C. In winter the temperature in this area reaches a few degrees above zero. Frost is a seldom event.
Along the highlands the climate is relatively temperate; cold and wet in winter with temperatures reaching a few degrees below zero during the night, to hot and dry in summer with temperatures reaching 35°C at noon, but with a relative humidity of 15-30%, which makes the heat more acceptable. During the hot summer, temperatures at night drop to less than 20°C and cause dew to form.
The plateau; the eastern and southern deserts are hot in summer and cold in winter. The temperature may reach more than 40°C during summer days and drop in winter to a few degrees below zero, especially during the night. Also here, the relative humidity is low. In winter it is generally around 50-60%, and in summer it sometimes drops to 15%. The low relative humidity throughout most of the year makes the hot summer days more tolerable and the cold winter days more severe.
The climatic conditions in Jordan do not only affect the amount and distribution of precipitation, but they also impact strongly the potentials of evaporation which range from about (1600mm/year) in the extreme northwestern edge of the country to more than (4000mm/year) in the Aqaba and Azraq areas. Along the rift valley the potential evaporation increases from a minimum of (2000mm/year) in the north, to some (2500mm/year) in the Dead Sea and to more than (4000mm/year) in Aqaba.