Is it dry or humid? This is the ultimate question when choosing what to wear.
Material matters "Your choice of fabric is crucial," says stylist and fashion writer Heather Newberger. "If you're wearing an oversized denim jumpsuit - you're going to feel way hotter than your friend in a more constricted outfit made of gauze or chiffon." When it comes to fit, lightweight woven fabrics such as cotton and silk are usually better at hanging loosely than knits. This is especially important when it's humid – in dry heat, wicking alone may be enough because the sweat will be absorbed from your body and evaporate in the heat. When it's humid and hot, the air around you is already saturated with water vapour, meaning the sweat your clothes just soaked up doesn't have anywhere to go. "In terms of clothes, it's better to have a material that allows water vapour to pass through so that it doesn't block the sweat evaporation." says Rhett Allain, associate professor of physics at Southeastern Louisiana University. "Some of the newer sports-based materials do this. Cotton does not do so great with this." All textiles trap infrared radiation given off by the body to some degree, which helps to keep us warm in cold weather – but isn't ideal…