It has warm, but not hot summers and mild winters. Due to its  altitude, temperatures are relatively mild for a city located not particularly far from the hotter surroundings in the country. This climate is characteristic of rainy, wet seasons and dry seasons. Asmara averages about  of precipitation annually. Frost, however, is extremely rare in the city. The long rainy season of the year extends from June until September. The short rainy season occurs from March until April. On average, about 60% of Asmara's annual precipitation is seen during the months of July and August. In contrast, December to February are typically Asmara's driest months, where on average only  of precipitation falls in the three months combined. Due to variable rainfall, Asmara's climate is also characterized by drought. Several prolonged droughts in this region have occurred beginning in the 1960s and have recurred each decade since then. During periods of drought, temperatures are high and little rainfall occurs. As temperatures in a region increase, the rate of evaporation of water from the soil also increases. These combined processes result in the desertification of the soil. In order to obtain nutrient rich and moist soil for farming purposes, populations rely on deforestation to make use of the underlying ground. The most serious environmental issues Asmara faces are deforestation and desertification. Other issues Asmara faces are soil erosion and overgrazing. All of these environmental issues produce soil degradation.