Japan's Weather

From Wiki-Whitehill

Visiting Japan can be enjoyable at any time of the year. Due to the country's large north-south extension, weather patterns differ dramatically between regions. Below is an introduction to each month of the year with respect to travel in Japan.
The tables list average daytime high and nighttime low temperatures and average percentages of sunny and rainy days for selected cities. A rainy day is defined as a day on which at least 1 mm of rain falls, while a sunny day is defined as a day on which the sun shines at least 40 percent during daytime.