You could be lucky and get dawn-to-dusk sunshine but, more often than not, hiking is an all-weather activity. That's what the Original Triclimate Jacket is for. You get three levels of protection in one package. Wear the polyester fleece inner jacket when it's cool but dry. Wear the outer DryVent™ shell layer for protection from rain and wind. And wear them together when the weather is doing its best to stop play: it's raining; the wind is blowing; and it's decidedly chilly but you still want to push on.