What's the temperature in Changbai Mountain Tianchi in mid-September?

It will be very cold in the northeast sooner or later, and the temperature difference is very large. It will be warm with the sun during the day. Changbai Mountain is different from other places. It is covered with snow all year round, with Tianchi and waterfalls. What's even more strange is that there are hot springs where eggs can be boiled. You should bring some winter clothes. In mid-September, the daytime temperature in mountainous areas should be around 17-20 degrees, and sometimes it may reach 65438 degrees at night. ! ! ! ! ! ! ! !