Why is Niigata not sunny?

There is no sunny day in Niigata because of the low temperature and humid climate. Niigata is a region of Japan, where there are great differences in temperature and precipitation between coastal areas and mountainous areas. The average annual temperature in coastal areas ranges from 12 to 13 degrees, while it is less than 10 degrees in inland areas. The temperature is very low, and the climate in Niigata is very humid. It rains every day, so there is no sunny day.