What's the weather like in Frankfurt, Germany in September?

Don't prepare too many clothes. Normal September is neither too cold nor too warm, but the weather in Germany in recent years is very strange, so you can't tell what it will be like then. Anyway, as long as men don't work outdoors, they must bring a suit, and then prepare some replacement shirts with one or two underwear inside, preferably one or two casual T-shirts and a coat. Pants are best not to be too thick or too thin. It is enough to bring a pair of trousers in the suit. Generally speaking, the temperature difference between morning and evening in September is relatively large, which may be more than 20 degrees during the day and about 10 degrees at night.