On any outing, extra clothing is key. A system to help remind you how much you should pack, but not too much, is to take the number of days you are staying, and divide it by 3. Then add that number to the amount of clothing you already have. On days of 3 and below, always just add 1. Another thing to keep in mind is that not all clothing necessarily applies to this method. Some clothes, like shoes or hats, only need an extra unit, as the weight of them is too excessive, and also it is unlikely you will go through two of these such things in a couple of days. But, always be prepared for the worst circumstances, but also try not to over pack!