Abadan has one of the most extreme climates of any inhabited city in the world. In summer — June through September — daytime temperatures regularly exceed 45°C, sometimes reaching 50°C, combined with high humidity from the river and the Gulf. Staying outdoors in the middle of a July day is genuinely dangerous. The city effectively shuts down during the hottest hours; those who can leave do.
November through February is the only sensible window for visiting. Daytime temperatures are mild, 15–25°C, with cool nights. Rain is light but possible. March is also acceptable but can be warm. April and May are bearable early in the month and then escalate quickly. October can still be very hot.
Even in the cool season, the industrial landscape, flat terrain, and persistent dust haze mean that Abadan is not a visually comfortable city. You come here for the history, not the scenery.