Weather in Fukuoka in September
Japan · 20-year averages, September
Shoulder season. September sits in between. You will get good days and you will lose some. The heat itself is manageable at 28.3 °C, but 85% humidity is what you will actually feel.
September ranks 5 of 12 in Fukuoka: past the worst of the year but short of October, which is the month to book if the dates are open.
This is wet-season rain: 13 wet days and 5 genuinely heavy ones, which in this climate means concentrated downpours rather than all-day grey. The pattern is usually a clear morning and a loud afternoon, so front-load the day and stop fighting the 3pm hour. Natural fibres and a second shirt for the day. At 85% nothing dries, including you.
What the averages hide
Averages flatten a month, and this one hides a few things: 9 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest September day reached 35 °C and the coldest night fell to 12.2 °C, and the wettest single day dropped 124 mm — roughly 66% of the month's rain in one day.
September is moderately variable: 65 mm in the driest year against 496 mm in the wettest, around an average of 189 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.
Wind is light at 3.9 km/h, so the temperature on the page is close to the temperature on your skin, and humidity at 85% is the real story though — it is the number that decides how the day feels, not the 28.3 °C.
How September sits in the year
The month is on the way down: 3.8 °C cooler than August, with October dropping another 5.3 °C. The first week and the last are not the same trip.
Daylight in September
12.4 hours of daylight, losing 1 hours across the month. That is between Fukuoka's extremes of 14.4 and 9.9 hours, so days are long enough not to constrain the plan.
Sea temperature
The sea sits at about 25.7 °C in September — warm enough to stay in as long as you like. This is the warmest the water gets all year.
How busy it gets
Shoulder. The value months — prices ease off and you get the place closer to itself.
Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.
September in Fukuoka versus nearby
If Fukuoka is one option among several, the nearby comparison is worth making. Kitakyushu is a better bet in September — within a degree on temperature, 1 day more rain. Hiroshima is close enough to be a coin toss — within a degree on temperature, the same number of rain days.
So: September is a compromise. October is 19 points better and is what Fukuoka is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.
Every month in Fukuoka
| Month | High °C | Low °C | Rain days | Rain mm | Humidity % | Daylight h | Sea °C | Score |
|---|---|---|---|---|---|---|---|---|
| January | 9.3 | 1.6 | 10 | 70 | 80 | 10.1 | 15.7 | 47 |
| February | 11.2 | 2.2 | 10 | 88 | 79 | 11 | 14.4 | 52 |
| March | 14.7 | 4.5 | 11 | 118 | 78 | 11.9 | 14.4 | 60 |
| April | 19.9 | 8.9 | 10 | 140 | 78 | 13 | 15.4 | 77 |
| May | 24.8 | 13.9 | 10 | 157 | 79 | 13.9 | 17.8 | 77 |
| June | 27.8 | 18.7 | 15 | 299 | 83 | 14.4 | 21 | 59 |
| July | 31.1 | 23.3 | 18 | 357 | 85 | 14.2 | 24.4 | 42 |
| August | 32.1 | 23.9 | 16 | 204 | 84 | 13.4 | 27.4 | 39 |
| September | 28.3 | 20.2 | 13 | 189 | 85 | 12.4 | 25.7 | 62 |
| October | 23 | 14.2 | 9 | 109 | 82 | 11.4 | 23.2 | 81 |
| November | 17.4 | 8.7 | 9 | 89 | 81 | 10.5 | 20.7 | 74 |
| December | 11.4 | 3.6 | 10 | 79 | 80 | 9.9 | 18 | 52 |
See all twelve months in Fukuoka, or where else to go in September.
Planning the rest of the trip
- Flight time to Fukuoka how long you are actually in the air
- Fukuoka time zone and the difference from home
- Days until your trip count down to the departure date