Along with shirts and pants, jackets are very important. You need to stay warm on mountains, so I suggest bringing a light weight, durable, puffer jacket or fleece. Both of these keep your core temperature high so you don’t get cold. Regular hoodies are too heavy and don’t keep you warm enough or break the wind. Remember as you get higher, the wind can get stronger. Regular street clothing just doesn’t work on mountains.
Pro Tip…
If you have the opportunity, purchase a windbreaker (outer shell). Windbreakers are jackets specifically designed to protect you from the wind which can be freezing depending on where you are.