In general, when booking your flight to Fukuoka, March is the cheapest month on average.
On average, from most locations, when planning your trip to Fukuoka, try to book your flight in the region of 43 days in advance for the cheapest prices.
In general, booking your departure to Fukuoka for a Tuesday represents the best deal on airfare. Try to avoid a Monday departure to stay away from the highest prices.
Generally, when visiting Fukuoka, morning flights represent the best value. midday flights are likely to have higher prices.