Welcome to Fukuoka City, one of the most populated cities in Japan (currently, 1.5 million people are living in Fukuoka) and the largest city in Kyushu Island. Kyushu is the third largest island of Japan, located at the southwestern part of the country. Fukuoka is situated at the northern area of the island.
September and October are very comfortable season. Weather information can be available on the following webpage.
http://www.weather-and-climate.com/average-monthly-Rainfall-Temperature-Sunshine,fukuoka,Japan