Ahvaz has one of the harshest climates of any Iranian city. Summer (June to September) is brutal — temperatures of 45°C to 50°C are not unusual, and dust storms are common. The city regularly appears in global rankings of hottest inhabited places on earth.
The ideal time to visit is November through March, when temperatures are mild (15–25°C) and the archaeological sites are pleasant to explore. Spring (April to May) is also acceptable but warms up quickly. Avoid public holidays if you are planning to visit Chogha Zanbil or Shush, as the sites become crowded.