What should I wear to Guilin on October 1st?

In recent days, the weather in Guilin is a little cold, with the temperature low in the morning (about 15~ 18 degrees) and high at noon (about 23~28 degrees), so long-sleeved T-shirts or thin coats are necessary. Old people should prepare thicker ones. I saw some old people wearing thick autumn clothes in the street, as if preparing for winter.