The weather in September in Holland

The average temperature in the Netherlands is 22 degrees in summer,-1 degree in winter, and the average monthly temperature in the whole year is about 16 degrees.

It is ok to wear short sleeves in summer, preferably a thin coat, and thick ones in winter, because the humidity in Holland is relatively high and it is biting when it is cold. It's ten to twenty degrees in spring and autumn, depending on your personal situation (whether you are afraid of the cold). Moreover, it will be windy and rainy in Holland, so it is a good choice to prepare a waterproof windbreaker with a hood.