[header] How to dress for hiking [title] Avoid heavy base layers if you plan on hiking in warm weather. [step] Long underwear is smart for colder weather, but it does not make much sense if you plan on hiking through the woods in the middle of summer. [title] Wear the right thickness of thermal underwear for cool weather. 
[step] Thermal underwear comes in light, mid, and expedition weights. The colder the conditions and the longer you plan on being out in them, the heavier you should go with.