During the summer months, temperatures can be mild, but the weather can still be unpredictable. A good rule of thumb is to pack a variety of clothing options, including both warm and lightweight layers. T-shirts, sweaters, and light jackets are all suitable options, as well as pants, shorts, and skirts depending on your personal preference. Waterproof or water-resistant footwear is still a good idea, as rain can occur at any time.
When visiting Iceland, it's important to be prepared for the weather conditions, as they can change rapidly. It's always a good idea to check the forecast before you pack and to bring along some extra layers just in case.