The cold of winter of the Sea of Japan side area along the shore is loose because of oceanic climate, and especially a southern part is warm.However, there are many days of snowstorm because of a heavy snowfall area.Moreover, since daylight hours are as short as about 2 hours per day, temperature seldom goes up also by daytime. Inland, although it is very cold in winter, a tropical day is observed in many cases and the difference of temperature is large in summer.It becomes cool the morning and evening and has become the climate which is easy to pass.
It is an area which a foehn(The phenomenon which moist air serves as a dry warm wind, and blows down across a mountain ) happens from spring easily in summer, may record an intensely hot day inland, and serves as high temperature most in Hokkaido.A tropical day may be observed even in May or June. However, heat does not last long but may dive to temperature to the extent that rain and sleet fall coldly at the time when the Sea of Okhotsk high pressure stagnates.That heat will recur again from July after that in August etc. is an area where a temperature difference is very large.
Doo (Sea of Japan side)
In the Sea of Japan side, although especially winter is warm in an area along the shore, there are much snowfall and snowfall and they serve as a heavy snowfall area. It may become drifting snow under the influence of a monsoon. Moreover, if a bomb cyclone hits directly, a heavy snowfall of 1 m or more may fall in a night.
Doo (Pacific Ocean side )
It is cool climate in the summer of the Pacific Ocean, and it is very rare for temperature to exceed 30 ℃.
By the area, a difference in temperature is intense and there are a warm area and a chill area in winter.
There are many daylight hours, and since they get comparatively warm in the daytime, they serve as quiet climate.
Although the whole region belongs to the Sea of Japan side climate mostly, in - winter, in Hokkaido, average temperature becomes high most under the influence of the Tsushima warm current in summer.
Since with few daylight hours the monsoon is strong, even if there is much snowfall, snow does not lie easily due to the influence of a wind and temperature in winter.Moreover, it becomes sultry in summer and a sultry night may be observed uniquely in Hokkaido.
■A typhoon and a rainy season do not come to Hokkaido?
In fact, a typhoon and a rainy season come.
However, a typhoon weakens influence, before landing at Hokkaido, and a typhoon can seldom be declared that it came.
Although the phenomenon in which a rainy season is called the "Ezo rainy season" and in which it is raining about two weeks occurs, the Meteorological Agency does not accept this to be a rainy season officially.
Therefore, Hokkaido is said for a typhoon and a rainy season not to come.