Afghanistan is variously described as being located within South Asia, Central Asia, and sometimes Western Asia (or the Middle East). Afghanistan is landlocked and mountainous, with plains in the north and southwest. The highest point is Nowshak, at 7,485 m (24,557 ft) above sea level. The climate varies by region and tends to change quite rapidly. Large parts of the country are dry, and fresh water supplies are limited. The endorheic Sistan Basin is one of the driest regions in the world.

Afghanistan has a continental climate with very harsh winters in the central highlands, the glaciated northeast (around Nuristan) and the Wakhan Corridor, where the average temperature in January is below −15 °C (5.0 °F), and hot summers in the low-lying areas of Sistan Basin of the southwest, the Jalalabad basin of the east, and the Turkistan plains along the Amu River of the north, where temperature averages over 35 °C (95 °F) in July. The country is frequently subject to minor earthquakes, mainly in the northeast of Hindu Kush mountain areas. Some 125 villages were damaged and 4,000 people killed by the May 31, 1998 earthquake.

The climate is typical of an arid or semiarid steppe, with cold winters and dry summers. The mountain regions of the northeast are subarctic with dry and cold winters. In the mountains bordering Pakistan, a divergent fringe effect of the monsoon, generally coming from the southeast, brings tropical air masses that determine the climate between July and September. At times, these air masses advance into central and southern Afghanistan, bringing increased humidity and some rain.