Short answer: Linen is the coolest and dries fast. Cotton is comfortable but holds sweat and dries slowly. Polyester dries quickly but can trap heat and smell. For humid heat, choose linen or a light, loose cotton.
In heat and humidity, comfort depends on two things: how well a fabric lets air through, and what it does with sweat.
Linen
Made from flax, linen is very breathable and dries quickly, so it feels cool even when you sweat. It creases easily and costs more, but it is the best choice for the hottest, most humid days.
Cotton
Cotton is soft, breathable and absorbs sweat well. The catch is that it holds that moisture and dries slowly, so a heavy cotton shirt can feel damp and heavy in humid weather. Light, loosely woven cotton, such as voile or mulmul, works much better than thick cotton or denim.
Polyester and other synthetics
Polyester absorbs very little water and dries fast, which is why sportswear uses it. Ordinary polyester clothing can feel hot and sticky, though, because it doesn't let air through as well, and it tends to hold on to body odour.
Rayon, viscose and blends
Rayon and viscose feel cool and drape well, but can be delicate when wet. Cotton-polyester blends dry faster than pure cotton and crease less, at some cost to breathability.
Tip: Fit matters as much as fabric. Loose clothes let air move against your skin; tight clothes trap heat whatever they're made of.
Quick guide
- Hottest, most humid days: linen, or loose light cotton.
- Monsoon and travel: quick-drying synthetic or blend, so things dry overnight.
- Exercise: technical, sweat-wicking synthetics.
- Everyday office wear: cotton-linen blends crease less than pure linen and stay cool.
Lighter colours reflect more sunlight and feel cooler in direct sun.
Questions people ask
Q: Is cotton bad in humidity?
A: Not bad, but slow to dry. Choose thin, loosely woven cotton and avoid thick fabrics like denim on humid days.
Q: Does linen shrink?
A: It can shrink a little, especially on its first wash or in a hot dryer. Wash cool and line dry.