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Karatsu, Japan climate

Cfa Humid subtropical

Karatsu has a seasonal mild-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is August with an average daily high near 32°C, while the coldest is January averaging around 3°C at night. Precipitation totals about 1991 mm a year and is strongly seasonal — July alone averages 349 mm while January barely receives 75 mm.

☀️ Summers
Hot
Highs near 32°C in August.
❄️ Winters
Chilly
Lows near 3°C in January.
🌧️ Rain
Very wet
About 1991 mm of rain a year.
Wettest in July
Sky & trend
Often grey
Overcast skies dominate much of the year.

Temperature & precipitation

Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figures TEMPERATURE °C 10°20°30°40° PRECIPITATION (mm) 0175350 JanAprJulOct

Hours of sunshine per day

Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER) 0h2h3h4h6h J: ~2.1 hours of sun/dayF: ~2.7 hours of sun/dayM: ~3.0 hours of sun/dayA: ~3.6 hours of sun/dayM: ~3.8 hours of sun/dayJ: ~2.6 hours of sun/dayJ: ~3.9 hours of sun/dayA: ~4.6 hours of sun/dayS: ~3.8 hours of sun/dayO: ~4.0 hours of sun/dayN: ~3.2 hours of sun/dayD: ~2.5 hours of sun/day JFMAMJJASOND Sun hours per day (est.)

Karatsu climate normals (1991–2020)

JanFebMarAprMayJunJulAugSepOctNovDec
Avg high (°C)101115192426303227231812
Avg temp (°C)671015192226282419148
Avg low (°C)33610151924242116105
Precipitation (mm)75851171461262803493141911278695
Jan – JunJanFebMarAprMayJun
Avg high (°C)101115192426
Avg temp (°C)6710151922
Avg low (°C)336101519
Precipitation (mm)7585117146126280
Jul – DecJulAugSepOctNovDec
Avg high (°C)303227231812
Avg temp (°C)26282419148
Avg low (°C)24242116105
Precipitation (mm)3493141911278695

Sky & atmosphere

JanFebMarAprMayJunJulAugSepOctNovDec
Cloud cover (%)797574727282726568646974
Relative humidity (%)757474767985868381767475
Wind speed (mph)9.18.88.57.36.15.65.86.17.47.97.88.8
Jan – JunJanFebMarAprMayJun
Cloud cover (%)797574727282
Relative humidity (%)757474767985
Wind speed (mph)9.18.88.57.36.15.6
Jul – DecJulAugSepOctNovDec
Cloud cover (%)726568646974
Relative humidity (%)868381767475
Wind speed (mph)5.86.17.47.97.88.8
Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from the Japan Meteorological Agency, measured at Karatsu, about 2 km from the city centre.

Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.

How we build these numbers →