Iran has a variable climate. In the north, winters are cold with heavy snowfall lower temperatures during December and January. Spring and fall are mild, while summers are hot and dry in Iran. Vice versa in the south, winters are mild and the summers are very hot.
In general, Iran has an arid climate in which most of the annual precipitation falls from October through April. In Iran, yearly precipitation averages 250 millimeters or less. The major exceptions are the higher mountain valleys of the Zagros and the Caspian coastal plain, where precipitation averages at least 500 millimeters annually. In the western part of the Caspian, rainfall exceeds 1,000 millimeters annually and is distributed evenly throughout the year.
Iran has four seasons, especially in Tehran, the capital, all the seasons are distinguishable. Summers are hot between 30to 40 degrees centigrade. In winter the temperature sometimes reaches to -10 degrees, and in spring and fall the temperature is mild.