There are many people who are recommending tourists to go to Iran between April and May, or September to November. From Iran climatology point of view, it is true. However, it really depends on what you want to do in which cities of Iran. Iran enjoys different types of weather from North to South, from East to West.
If you want to know when is the best time for Iran business trip, we should tell you that it doesn’t matter when to go as long as it is not in holidays. There are two kinds of holidays that stop you from doing official business in Iran. The first one is Norooz, Iranian New Year. It starts from 21st of March and dependent on the considered business, it lasts for 5 official days. However, one should remember that a couple of days before starting Norooz, companies are in New Year celebration mood 🙂 so, maybe you should plan your trip to end before 20th of March.
The second holiday is religious. We have many religious holidays which you can check here. But, they are not as important as the week before Ashoora. The official holiday takes only two days, though some people, or companies are involved in religious traditions. This, again, depends on the business that you are interested in.