Just came back from Hainan, relatively speaking
Haikou

The climate is still relatively hot. Local young people basically wear short-sleeved shirts during the day, while middle-aged and elderly people wear long-sleeved shirts. The temperature difference between morning and evening is not obvious, but it is safer to bring a jacket to prevent accidental cooling.

If you think his answer is good, please give him a like!
Your support is a great encouragement to the author~