Travelling to Fukuoka on 10/21/2016

Why are most hotels already booked during this period, especially in Hakata district?

Friday night...?

Just checked, this on has vacancies:-

http://hakata.theb-hotels.com/en/

Thank You. I have found hotel in Hakata. Just curious is this a busy travel period or holiday? I note many more rooms available in the following week?

Not a holiday time at all - there is Health-Sports Day (‘̈ç‚Ì“ú) but that is on Oct. 10, nor is it anytime near the 2 main festival times in Hakata during the year.
There could be some concert or something; that has caused some full hotels before but it is hard to pin down. The fact that it is a weekend certainly doesn't help - when I was going to Kochi-shi I had trouble getting a hotel too on a weekend - and that is a much smaller place with less happening.

Good that you found a room though.

If you're going to be seeing the sights, look into getting a subway day pass - many of the better places to see are not far from a station.
https://www.youtube.com/playlist?list=PL7LcPcmoSg-j4RLa6iC7ayvBAbOn8-0...
http://www.thejapanfaq.com/fukpic.html

Alternatively if you'll need the bus, there is the Fukuoka Tourist City Pass (if you qualify):
https://yokanavi.com/en/tourist-city-pass/
It also has discounted admissions to many popular places.

I have found in Fukuoka, especially close to Hakata Station that all the cheaper hotels like Toyoko Inn for example (less than 8000 per night) are all booked out 3 months in advance both on Fridays and Saturdays. Doesn't matter whether holidays or not.

I've been in April for 3 days in this hostel and I can only say that it is all good, very clean and cheap, checked if there were vacancies at that time that you spoke and this free !! I paid 7.500yen
Fukuoka Hana Hostel •Ÿ‰ª‰Ô�h
Adresse: 4-213 Kamikawabatamachi, Hakata Ward, Fukuoka, Fukuoka Prefecture 812-0026, Japan
Telefon:+81 92-282-5353

Many thanks to you all!