Let me just chime in for the synthetics. I love cotton, always have, but if I am wearing this because it is hot out, I a going with synthetics because they feel better wet and dry much faster. I am far more likely to have a problem with heat exhaustion or dehydration than fire. The only time I conciously selected natural fabrics over synthetics is when I was onboard submarines. You cannot run away. Otherwise the risk of synthetics melting to you is far less than the benefits of synthetics in hot environments.

Bill