Dressing at twenty degrees
Short answer: One layer is enough. Twenty degrees is the temperature where the choice of fabric matters more than the number of layers.
What the body does at twenty degrees
The body does not have to work to stay warm, but it is not pushed to cool down either. That is why a fabric that sits lightly against the skin and lets air pass is enough.
The fabric that works
Bamboo viscose feels cool because it carries heat away from the skin faster than cotton. At twenty degrees that difference is clear in a close fitting t-shirt. See bamboo t-shirts for men.
What to bring
A thin layer for the evening and for indoor places with air conditioning. See bamboo clothing for women and bamboo dresses.
Frequently asked questions
Should you wear socks
With closed shoes yes. Bare feet put moisture and smell into the shoe.
Is twenty degrees too warm for long trousers
No, if the fabric is light. Dense synthetic trousers get warm.
What about a jacket
Only if there is wind or you will be out after sunset.