Ōkawa weather in September

In September, Ōkawa sees average daytime highs of 28°C and overnight lows near 20°C, with 180 mm of rain across 12 wet days and about 12.2 hours of daylight. It is the 3rd-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 30°C in the first days to 26°C by the end. The sky is clear or mostly clear about 34% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 42 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Ōkawa's 3rd-clearest and 8th-windiest month. For the whole year in context, see Ōkawa's year-round climate.

Daytime high
28°
3rd warmest
Overnight low
20°
10th coldest
Rainfall
180 mm
12 wet days
Daylight
12 h 12 min
6:07 AM – 6:19 PM
Cloud cover
59%
3rd clearest
Wind
8 km/h
8th windiest
Solar energy
4.12 kWh/m²
Travel score
5.7
out of 10

Ōkawa is city in Fukuoka Prefecture, Japan.

Density
1,166/km²
people per km²
Founded
1954

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 30°C in the first days to 26°C by the end.

A typical September day in Ōkawa reaches about 28°C in the afternoon and slips back to 20°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 25°C and 31°C. Set against its neighbours, September runs about 3°C cooler than August and about 5°C warmer than October.

10°15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
13023
23022
33022
43022
53022
62922
72922
82922
92921
102921
112921
122921
132921
142821
152820
162820
172820
182820
192820
202719
212719
222719
232719
242719
252718
262718
272618
282618
292618
302617

How September really feels in Ōkawa

Once humidity and wind are folded in, September averages 5 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
5
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Ōkawa weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan10° / 6180.710.12.3
Feb11° / 808.60.410.82.8
Mar15° / 12811.30.111.74.3
Apr20° / 10°14711.3012.85.9
May24° / 15°17011013.76.6
Jun26° / 19°37216.6014.25.3
Jul30° / 23°33417.50144.2
Aug31° / 24°17514.3013.24.0
Sep28° / 20°18012012.25.7
Oct23° / 14°1067.8011.27.3
Nov18° / 898.1010.35.9
Dec12° / 707.50.19.83.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 34% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 50%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14753
24753
34852
44852
54951
64852
74852
84951
95050
105050
115149
125149
135149
145149
155149
165149
175149
185050
195050
205149
215149
225149
235149
245149
255149
265248
275248
285248
295347
305347

Chance of precipitation in September

Any precipitation

Ōkawa gets around 180 mm of rain over 12 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 39% and peaks near 47% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
147
247
346
446
545
645
744
844
943
1043
1142
1241
1341
1440
1539
1638
1738
1837
1937
2036
2136
2235
2335
2435
2534
2634
2734
2833
2933
3033

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the oppressive band about 31% of days. Sticky, muggy-or-worse air turns up on roughly 63% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1008255512
2019275211
30110285110
4011129509
5011230498
6021330477
7021431466
8021631446
9131732435
10141832415
11151932395
12152032374
13262131354
14282231334
15392331313
163102430293
174112530283
185122629262
195132728242
206152728232
217162827212
227172927191
238192926181
249202925161
259212925151
2610222924141
2711232923121
2812242922111
2914252922101
3015252821101

Wind in September

Winds average 8 km/h in September.

Across September, daily wind ranges from about 8 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
218calm
228calm
238calm
248calm
258calm
268calm
278calm
288calm
298calm
308calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 42 min at the start of September to 11 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 60 minutes over September. Sunrise moves from 5:57 AM to 6:17 AM, and sunset from 6:40 PM to 5:59 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.75:576:40
212.75:576:38
312.75:586:37
412.65:596:36
512.65:596:34
612.66:006:33
712.56:016:32
812.56:016:30
912.46:026:29
1012.46:036:27
1112.46:036:26
1212.36:046:25
1312.36:056:23
1412.36:056:22
1512.26:066:20
1612.26:076:19
1712.26:076:17
1812.16:086:16
1912.16:096:15
2012.16:096:13
2112.06:106:12
2212.06:116:10
2312.06:126:09
2411.96:126:08
2511.96:136:06
2611.96:146:05
2711.86:146:03
2811.86:156:02
2911.76:166:00
3011.76:175:59

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.12 kWh/m².

For context, solar energy here swings from a low near 2.2 kWh/m² to a high of 5.24 kWh/m² in May across the year — September's 4.12 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.4Bright
24.4Bright
34.4Bright
44.4Bright
54.3Bright
64.3Bright
74.3Bright
84.3Bright
94.3Bright
104.3Bright
114.2Bright
124.2Bright
134.2Bright
144.2Bright
154.2Bright
164.1Bright
174.1Bright
184.1Bright
194.1Bright
204.1Bright
214.0Bright
224.0Bright
234.0Bright
244.0Moderate
254.0Moderate
263.9Moderate
273.9Moderate
283.9Moderate
293.9Moderate
303.9Moderate
Planning a trip in September

Hazard calendar for Ōkawa

In seasonPeak

In September, Ōkawa sits inside its pacific typhoon and rainy season season. The full year is below, with each hazard's peak months called out.

Ōkawa sits in the Pacific typhoon belt; the season peaks July–October.

Ōkawa's rainy season runs May–September, when most of the year's rain falls.

Pacific typhoon
Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Ōkawa?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

5.7
Sightseeing
5th-best month of the year
6.4
Beach & pool
1st-best month of the year

September is a reasonable time to visit Ōkawa for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Ōkawa in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Ōkawa sees daytime highs around 28°C and nights near 20°C. Pack light clothes. Worth having: rain gear. About 12 days see rain.

light clothesrain gear

Sea temperature near Ōkawa in September

The nearest coast averages about 26°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 27°C and coldest in February near 13°C.

It's comfortable for a long swim from May 27 to Nov 12 — about 5.6 months when the water holds above 20°C.

10°15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan14Bracing
Feb13Bracing
Mar14Bracing
Apr16Cool
May19Cool
Jun22Refreshing
Jul25Warm
Aug27Warm
Sep26Warm
Oct23Refreshing
Nov20Cool
Dec17Cool

UV index in Ōkawa in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Ōkawa peaks around July 18 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJul 18UV 10Dec 22UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar6High
Apr8Very high
May8Very high
Jun8Very high
Jul10Very high
Aug9Very high
Sep9Very high
Oct7High
Nov4Moderate
Dec3Moderate

Air quality in Ōkawa in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Ōkawa is worst in March — around 25 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (July, 13 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateMar 2325 µg/m³Jul 2114 µg/m³
PM2.5 (µg/m³)Level
Jan18Moderate
Feb20Moderate
Mar25Moderate
Apr25Moderate
May23Moderate
Jun19Moderate
Jul13Moderate
Aug15Moderate
Sep14Moderate
Oct14Moderate
Nov16Moderate
Dec15Moderate
Location & terrain

Where is Ōkawa?

Ōkawa sits at 33.2°N, 130.4°E, 4 m above sea level, in Japan. The nearest listed city is Yanagawa, 5.0 km away.

Topography around Ōkawa

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Ōkawa.

Within 3 km, the terrain around Ōkawa has only modest variations in elevation — a maximum elevation change of 15 m around an average of 3 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 355 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,685 m.

The land around Ōkawa is covered by artificial surfaces (46%) and cropland (39%) within 3 km, cropland (45%), artificial surfaces (25%) and water (20%) within 16 km, and trees (49%) and water (32%) within 80 km.

3 km
15 m
16 km
355 m
80 km
1,685 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Yanagawa 5.0 km · Saga 8.0 km · Setakamachi-takayanagi 11 km · Chikugo 11 km · Kanzakimachi-kanzaki 11 km · Nakatsukuma 15 km · Miyama 15 km · Hirokawa 17 km

Japan travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B
100 V · 50 / 60 Hz
Prices
≈ 65% of US
price level, 2025
GDP per capita
$35,951
2025
Happiness
6.1 / 10
World Happiness, 2025
Safe drinking water
99%
of population, 2024
Homicide rate
0.2
per 100k, 2023
Road deaths
3.6
per 100k/yr, 2019
Income group
High
World Bank
English
Very low
EF EPI 446
Religion
Shintoism 49%Buddhism 46%other 4%Christianity 1%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Ōkawa (33.2057°, 130.3753°, elevation 4 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).