What clothes to take on a hike? I need to pack some clothes for the trip this spring. I know that in the morning and at night it can be very cool. I decided to take a set of thermal underwear, but we go on a hike for 4 days, I'm not sure that one set of thermal underwear is enough. If it rains, my clothes will quickly get wet and will not be able to dry quickly. But I can't take a lot of clothes with me.