When to go
Given the vastness of Iran and its different climates, it is difficult to find a period that is best for all the country, however, you can choose
spring and autumn to avoid the winter cold (present especially in the north and at high altitudes) as well as the summer heat (present almost everywhere).
You can choose
spring, in particular the month of April, which, however, can still be a bit cold in the north and in the mountains, and can already be hot in the south, in the Persian Gulf and the Gulf of Oman, and even more so in Sistan and Baluchistan.
Autumn can be nice as well, especially the month of October, but in the south, it's even hotter than in April, while it may be rainy on the Caspian Sea.
What to pack
In
winter: on the coast of the Caspian Sea, bring warm clothes, such as a sweater, a jacket, and a raincoat or umbrella. In Tabriz, the northern plateau and high mountains, very warm clothes, such as a down jacket, a hat, a scarf, and gloves. In Tehran and Isfahan, warm clothes, such as a sweater, a coat, and a hat. In the Lut Desert, spring/autumn clothes (light for the day), a sweater, a jacket, and a scarf for the sand. On the coast of the Persian Gulf and in Bandar-e-Abbas, spring/autumn clothes, a jacket and a sweater; for the Gulf of Oman, spring/autumn clothes (light for the day), a light jacket and a sweater.
In
summer: on the coast of the Caspian Sea, bring light clothes, a light sweatshirt for the evening, a scarf for the breeze, and possibly a light raincoat or umbrella. In Tehran and the major cities of the plateau, loose-fitting, light-colored clothing, light and long shirts and pants of natural fibers (cotton, linen), a wide-brimmed hat, sunglasses, comfortable and breathable shoes, a desert turban, and a sweatshirt for the evening. Above 2,000 meters (6,500 feet), you can add a jacket for the evening.
On high mountains, bring warmer clothes depending on the altitude. On the shores of the Persian Gulf and the Gulf of Oman, bring tropics-friendly, lightweight clothes, a desert turban, a sweatshirt and a scarf for air conditioned.
When visiting mosques, you must cover your shoulders and knees, and take off your shoes. Women should avoid low-cut dresses.
Back to the climate of
Iran