Iran has a diverse terrain, and the climate, depending on where you are, can vary from subtropical to subpolar. On average, Iran has dry summers and cool winters. In Tehran, January is the coldest month (8 degrees Celsius) and July-August the warmest months (36-37 degrees). The peak season for travel is from March to May because of the mild weather and the celebration of the No Ruz or Iranian New Year, which usually occurs on March 21. The shoulder months of September and October have moderate weather, while the winter months (November to February) are usually avoided due to the extreme cold (unless you’d like to go skiing!).