Climate averages 1991–2020
Karatsu weather
in September.
A warm, wet month: the 3rd warmest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Karatsu: daytime highs average 27.0°C and nights cool to about 21.8°C. By daytime temperature it is the 3rd warmest of the 12 months.
Expect about 179 mm of rain on roughly 13 days, which makes September a wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 25 min on an average September day.
The nearest other city in this atlas is Itoshima (23 km away). In September its highs average 26.6°C, about as warm as Karatsu, with 180 mm of rain.
Among the 303 cities listed in Japan, Karatsu ranks joint 59th of 303 for the warmest September highs and joint 115th of 303 for the driest September (rainfall, lowest first). The mean September high of those 303 cities is 25.7°C; Karatsu is 1.3°C warmer than that mean.
From September to October, average highs fall by 4.8°C to 22.1°C, and monthly rainfall falls from 179 mm to 103 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Karatsu climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 9.0°C4.5°C | 4.5°C | 76 | 11.9 | 10.210 h |
| February | 10.2°C4.6°C | 4.6°C | 80 | 10.5 | 11.011 h |
| March | 13.6°C7.1°C | 7.1°C | 124 | 11.6 | 12.012 h |
| April | 18.4°C11.0°C | 11.0°C | 134 | 11.0 | 13.013 h |
| May | 22.7°C15.6°C | 15.6°C | 143 | 10.3 | 13.914 h |
| June | 25.6°C19.8°C | 19.8°C | 277 | 14.7 | 14.314 h |
| July | 29.1°C24.1°C | 24.1°C | 260 | 15.3 | 14.114 h |
| August | 30.4°C25.1°C | 25.1°C | 162 | 13.7 | 13.413 h |
| September, selected | 27.0°C21.8°C | 21.8°C | 179 | 12.6 | 12.412 h |
| October | 22.1°C16.7°C | 16.7°C | 103 | 8.1 | 11.411 h |
| November | 16.8°C11.5°C | 11.5°C | 94 | 9.3 | 10.510 h |
| December | 11.4°C6.7°C | 6.7°C | 81 | 11.1 | 10.010 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Itoshima in SeptemberJapan · 23 kmHigh 26.6°C · Low 21.7°C · 180 mm rain
- Maebaru-chūō in SeptemberJapan · 25 kmHigh 26.3°C · Low 21.9°C · 180 mm rain
- Sasebo in SeptemberJapan · 38 kmHigh 27.0°C · Low 22.0°C · 186 mm rain
- Saga in SeptemberJapan · 39 kmHigh 27.1°C · Low 20.2°C · 189 mm rain
- Fukuoka in SeptemberJapan · 45 kmHigh 27.1°C · Low 20.9°C · 179 mm rain
- Kasuga in SeptemberJapan · 47 kmHigh 27.4°C · Low 20.2°C · 179 mm rain
- Tosu in SeptemberJapan · 51 kmHigh 27.4°C · Low 19.8°C · 180 mm rain
- Kurume in SeptemberJapan · 53 kmHigh 27.5°C · Low 19.6°C · 180 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Karatsu) is explained once on the Karatsu year overview and on the Sources, method and limits page.