Climatically, Pakistan enjoys a considerable measure of variety. North and north western high mountainous ranges are extremely cold in winter while the summer months of April to September are very pleasant. The plains of the Indus valley are extremely hot in summer with a cold and dry weather in winter. The coastal strip in the South has a moderate climate. There is a general deficiency of rainfall. In the plains annual average ranges from 16 centimeters in the northern parts of lower Indus plain to 120 centimeters in the Himalayan region. Rains are monsoonic in origin and fall late in summers. Due to the rainfall and high diurnal range of temperature, humidity is comparatively low. Only the coastal strip has high humidity. The country has an agricultural economy with a network of canals irrigating a major part of its cultivated land. Wheat, cotton, rice, millet and sugar cane are the major crops. Among fruits: mangos, oranges, bananas and apples are grown in abundance in different parts of the country. The main natural resources are natural gas, coal, salt and iron. The country has an expanding industry. Cotton, Textiles, sugar, cement, and chemicals play an important role in its economy. It is fed by vast hydroelectric power.