Wear short sleeves inside and a down jacket outside when you go. I wore cotton trousers below, and went to the toilet to take off my cotton trousers and only wore a pair of jeans after boarding the plane.
Sanya is not cold, it's over 20 degrees, and you can wear skirts, shorts and short sleeves. Take a thin coat with long sleeves. It's really cold in the morning and evening. I like to get up early in the morning and go to Yalong Bay, and sometimes I wear a down jacket to go haha. It's either cold or afraid of the wind, and the Russians next to it are walking barefoot, cow.
Wearing a skirt on the plane will be a little cold, because it is basically controlled by the standard temperature of 24 degrees, but if there is a blanket on the plane, you can ask him for a blanket to cover it, so it won't be so exaggerated.
Also, don't bring a bunch of useless clothes. Go to the first market and see, all of them are swimsuits, swimming trunks, beach shoes, beach pants and bohemian skirts. The price is definitely cheaper than what you bought at home or online. Buy it now.
Don't put cotton trousers and down jacket in your carry-on bag when you go back. Put them on before getting off the plane.