Climate of Hokuriku district

In winter (December-January-February), the Siberian High develops over the Eurasian Continent and the Aleutian Low develops over the northern North Pacific. Prevailing northwesterly winds cause the advection of cold air from Siberia to Hokuriku and bring heavy snowfall to the area, especially in mountainous parts. The frequency of thunder storms in Hokuriku is the highest in winter, as opposed to other districts of Japan where the peak is in summer.

In spring (March-April-May), migratory cyclones and anticyclones that alternately move eastward prevail across Japan. Temperature increases (decreases) in front (back) of cyclonic systems due to warm southerly (cold northerly) flow. Temperature in Hokuriku rises gradually with large short-term variations. The sunshine duration is long in the second half of spring due to the predominance of anticyclonic systems.

The period from the middle of June to late July is the rainy season (called the Baiu). Its precipitation is caused by a stationary front, called the Baiu front, which forms where a warm maritime tropical air mass meets a cool polar maritime air mass. In the second half of summer, the North Pacific High extends northwestward around Japan, bringing hot, humid, and sunny conditions to Hokuriku. Southerly winds around the western edge of the North Pacific High sometimes bring very hot air to Hokuriku (the Foehn phenomenon).

In autumn (September-October-November), temperatures in Hokuriku fall gradually. The autumnal rain front and tropical cyclones affect the autumn weather of Hokuriku. The frequency of cold northwesterly flows across Japan and precipitation (rainfall or snowfall) in Hokuriku show an increasing tendency in November.