Summer The climate from June to September is marked by hot, wet weather brought by tropical airflows from the Pacific Ocean and Southeast Asia. with the annual precipitation is one of the world's highest at 4,000 to 10,000 mm. Maximum precipitation, like the rest of East Asia, occurs in the summer months except on the Sea of Japan coast where strong northerly winds produce a maximum in late autumn and early winter. Except for a few sheltered inland valleys during December and January, precipitation in Japan is above of rainfall equivalent in all months of the year, and in the wettest coastal areas it is above per month throughout the year. Mid-June to mid-July is generally the
rainy season in Honshu, Shikoku, and Kyushu, excluding Hokkaidō since the seasonal rain front or dissipates in northern Honshu before reaching Hokkaido. In Okinawa, the rainy season starts early in May and continues until mid-June. Unlike the rainy season in mainland Japan, it rains neither every day nor all day long during the rainy season in Okinawa. Between July and October, typhoons, grown from tropical depressions generated near the equator, can attack Japan with furious rainstorms.
Winter range in
Miyagi Prefecture In winter, the
Siberian High develops over the Eurasian land mass and the
Aleutian Low develops over the northern Pacific Ocean. The result is a flow of cold air southeastward across Japan that brings freezing temperatures and heavy snowfalls to the central mountain ranges facing the Sea of Japan, but clear skies to areas fronting on the Pacific. The warmest winter temperatures are found in the
Nanpō and
Bonin Islands, which enjoy a tropical climate due to the combination of latitude, distance from the
Asian continent, and warming effect of winds from the Kuroshio, as well as the Volcano Islands (at the latitude of the southernmost of the Ryukyu Islands, 24° N). The coolest summer temperatures are found on the northeastern coast of Hokkaidō in
Kushiro and
Nemuro Subprefectures. ==Sunshine==