This book clarifies the climatic variations in Japan from the historical period to the present based on documentary sources and meteorological data. Japanese society has suffered from various kinds of natural disasters since ancient times, such as floods and high tides caused by torrential rainfall and strong winds. They were described in large numbers of historical documents including official local weather diaries. However, all these documents were written in Japanese or Chinese languages, which prevents non-readers of those languages from accessing them. Also, Japan is a Far Eastern island country, and the unique features of Japanese climate and natural disasters would be unfamiliar and unimaginable to them without being able to read those documents. How is the climate of Japan, and how was the climate during the Little Ice Age in Japan as compared with conditions in Europe and America? When did meteorological observations start, and who (which country) introduced them to Japan? Why did so many natural disasters occur in Japan, and what caused them? This book answers these questions as specifically and objectively as possible using both figures and photographs, which are beneficial to students and the general public who are interested in historical and current climatic change in Japan, as well as professional climate scientists.