The abundance of landslides that occurred in Taiwan in August of 2009 is not only attributed to extremely heavy rainfall but also extreme weather change from a dry period that occurred one month before the landslides to extremely heavy rainfall within a few days when Typhoon Morakot passed through Taiwan. The dry month of July in the summer of 2009 followed several months of rainfall shortage. Numerous cracks and fissures would have developed in the ground surface. Those cracks and fissures enabled the heavy rainfall to easily infiltrate the ground, thus constituting another factor causing a huge number of landslides in southern Taiwan. Thus, warning against abundant landslides might be considered in the future as extremely heavy rainfall can occur during the hot, dry summer season.