Iran is a large country three times the size of France. It is bordered by Turkmenistan, the Caspian Sea, Azerbaijan, and Armenia on the north; Afghanistan and Pakistan on the east; the Gulf of Oman and the Gulf on the south and southwest; Iraq on the west; and Turkey on the northwest.
Much of the interior consists of a high plateau between 900-1,500 m/3,000-5,000 ft above sea level. The Iranian plateau is surrounded on all sides by mountains: the Elburz ranges on the north and the Zagros on the west and south. In the higher parts these mountains rise to between 3,000 m/10,000 ft and 4,600 m/15,000 ft, so that winter snows feed many of the country's rivers.
Much of Iran has a very harsh climate with great extremes of heat and cold between summer and winter. Large portions of central, southern and eastern Iran consist of desert and steppe with annual precipitation below 300 mm/12 in.
With the exception of the northern slopes of the Elburz Mountains and the Caspian coastlands, rainfall is confined to the winter and spring months. In the extreme north of the country some rainfall occurs throughout the year.
Summers are everywhere warm to hot with almost continuous sunshine. Winter weather is changeable with a mixture of mild, wet spells and some very cold weather with frost and snow when cold air blows from Siberia.
Along the shore of the Gulf and Arabian Sea winters are much milder as shown by the tables for Abadan and Bushire. The high temperatures experienced here in summer are similar to those in lowland Iraq and there is a danger of heat exhaustion and even heatstroke.
Temperatures in the interior plateau are considerably lower in winter but are very high during the long sunny summer (see the tables for Tehran and Isfahan). In the southern coastlands the high humidity makes the high temperatures even more unpleasant in summer.
In the interior daytime humidity is usually quite low in summer and the most dangerous conditions arise when high temperatures are combined with occasional strong, dusty winds.
The small area of Iran along the Caspian coast has a very different climate from the rest of the country. Here precipitation is heaviest from late summer until midwinter and occurs around the year. This region is much wetter and cloudier than the interior and the annual precipitation ranges from 800 mm/35 in to 2,000 mm/80 in.
It is a fertile, well-forested region and contrasts in a startling way with the arid landscape of interior Iran, where most cultivation is dependent upon irrigation from underground water resources and streams fed by rain and snow falling on the surrounding mountains.
Spring and autumn are quite short seasons in Iran between the heat of summer and the more changeable and often cold weather of winter. These seasons are the best time to visit Iran even if the weather may, on occasions, be a little uncertain with short lapses into either the cold of winter or the heat of summer.
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