Iran has a variable climate. In the northwest, winters are cold with heavy snowfall and subfreezing temperatures during December and January. Spring and fall are relatively mild, while summers are dry and hot. In the south, winters are mild and the summers are very hot, having average daily temperatures in July exceeding 38° C. On the Khuzestan plain, summer heat is accompanied by high humidity.

In general, Iran has an arid climate in which most of the relatively scant annual precipitation falls from October through April. In most of the country, yearly precipitation averages 25 centimeters or less. The major exceptions are the higher mountain valleys of the Zagros and the Caspian coastal plain, where precipitation averages at least 50 centimeters annually. In the western part of the Caspian, rainfall exceeds 100 centimeters annually and is distributed relatively evenly throughout the year. This contrasts with some basins of the Central Plateau that receive ten centimeters or less of precipitation annually.

Data as of December 1987

NOTE: The information regarding Iran on this page is re-published from The Library of Congress Country Studies and the CIA World Factbook. No claims are made regarding the accuracy of Iran Climate information contained here. All suggestions for corrections of any errors about Iran Climate should be addressed to the Library of Congress and the CIA.