What's the weather like in Dalian at the end of September? Is a long-sleeved shirt enough?

Nowadays, people wear long-sleeved coats indoors, and it is still a bit rare to go to the seaside alone in a long-sleeved shirt. It's impossible to get into the water, but it's ok to play. If you really want to get off, go to the water park. Seawater doesn't work. It is most appropriate for you to wear a long-sleeved shirt inside and a thin coat outside. If it is hot at noon, take off your coat.