The frequencies of thunder days in various regions in Japan have been investigated for the past 100 years. During this period the temporal variation of winter thunder-day frequencies along the Japan Sea coast and that of summer thunder-day frequencies on the inland area of the Kanto Plain shows some characteristic features. The former indicates a negative and the latter a positive correlation with the temperature variation of the northern hemisphere. While the variation of thunderstorm activities in most parts of Japan is controlled by local weather and climate changes, the above two categories of thunderstorm activities appear to be affected by global-scale temperature variation. ¿ American Geophysical Union 1989