The standard advice I used to hear was to never wear synthetics in hot climates, because they'd be terribly uncomfortable! Instead you were advised to wear only natural fibers in the heat, particularly cotton and linen, because they were more "breathable".
What I also find interesting is that many of the 'new' synthetics, including the "Bamboo" derived ones, are basically updated versions of Rayon, a fiber that had a terrible reputation in the 80s and 90s (and was typically associated with very cheap faux-silk clothing that was hard to wash and harder to keep unwrinkled). Some of my older family members were shocked to find out that the high-tech synthetics were made from wood pulp in a manner similar (although obviously much improved) to the 'manufactured silk' of the early/mid 20th century.
High-tech synthetics came a long way and are robust as hell. I have little kids and they are little ruffians. None of the synthetic shirts ever buckled
Wet wool is still warm and dries _really_ fast.
