We have found the best way to be ready for the varying conditions we encounter is to plan our wardrobe around layers. Our clothing choices are made with durability, comfort, wick-dry, and weight considered. Each piece of clothing needs to serve a dedicated purpose, dry quickly, and easily mix with other items chosen.
For example; The Andes (high elevation) can be cool and raining during the early mornings and afternoons, hot during midday, and chilly to cold at night. This is where layering becomes necessary. Bright colors are usually avoided to reduce any attention to our presence. Black, or darker colors, are also avoided because of the intensity of the sun at higher elevations. We often shop local markets for inexpensive pull-overs to supplement our wardrobe. These items can easily be traded later if we need to.
The conditions are much different once you enter the Amazon Rainforest (low elevation). It can be chilly for awhile after a storm, but it is never cold. Days are usually hot and steamy, and evenings can be warm and humid so close to the equator. Lightweight long sleeve shirts and full length pants are our first choice in clothing. We consciously dress for protect ourselves against biting insects, avoiding white of bright colors because these attract insects to you. Regardless of the temperatures, the attire we choose while in the Amazon is more for protection than comfort. There is little layering needed here.
Regardless of our destination we always choose clothing that quickly wick drys (including socks). This feature is essential.