Kōzan weather in September

In September, Kōzan sees average daytime highs of 28°C and overnight lows near 20°C, with 160 mm of rain across 11 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 29% of the time in September, and the air most often feels muggy.

Daylight stretches from about 12 h 48 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Kōzan's 9th-clearest and 9th-windiest month. For the whole year in context, see Kōzan's year-round climate.

Daytime high
28°
3rd warmest
Overnight low
20°
10th coldest
Rainfall
160 mm
11 wet days
Daylight
12 h 12 min
5:56 AM – 6:09 PM
Cloud cover
62%
9th clearest
Wind
8 km/h
9th windiest
Solar energy
4.17 kWh/m²
Travel score
5.7
out of 10

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 Kōzan 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 24°C and 31°C. Set against its neighbours, September runs about 4°C cooler than August and about 6°C warmer than October.

10°15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
13022
23022
33022
43022
53022
63022
73022
82921
92921
102921
112921
122921
132920
142820
152820
162820
172820
182819
192719
202719
212719
222718
232718
242618
252618
262618
272617
282617
292517
302517

How September really feels in Kōzan

Once humidity and wind are folded in, September averages 3 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
3
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.

Kōzan 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
Jan / 435.419.91.8
Feb10° / 547.21.410.72.2
Mar14° / 959.90.411.73.9
Apr19° / 1109.7012.86.0
May23° / 14°1299.9013.86.8
Jun26° / 19°19212.8014.35.8
Jul30° / 23°20713.7014.14.4
Aug32° / 24°12512.2013.33.9
Sep28° / 20°16011012.25.7
Oct22° / 13°1037.6011.17.2
Nov17° / 596.6010.25.7
Dec11° / 505.90.49.73.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 29% 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 55%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14555
24654
34654
44654
54654
64654
74654
84555
94456
104555
114555
124654
134654
144555
154555
164555
174555
184456
194456
204555
214555
224555
234555
244654
254654
264654
274654
284852
294951
304951

Chance of precipitation in September

Any precipitation

Kōzan gets around 160 mm of rain over 11 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 37% and peaks near 41% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
141
241
341
440
540
640
739
839
939
1039
1138
1238
1338
1437
1537
1636
1736
1836
1935
2035
2135
2234
2334
2434
2533
2633
2733
2832
2932
3032

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the muggy band about 27% of days. Sticky, muggy-or-worse air turns up on roughly 51% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1031535452
2041635441
3051735421
4061834411
5061934391
6072034381
7182134361
8192233341
91102233331
101112332311
112132432291
122142431281
133152530260
144172529250
155182529230
166192628210
177202627200
188212626180
199232725170
2010242725150
2111252724140
2212262723120
2313272822110
2414282821100
251529282090
261729281980
271830281870
281931271760
292131271650
302232271540

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 48 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 66 minutes over September. Sunrise moves from 5:45 AM to 6:06 AM, and sunset from 6:30 PM to 5:48 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:456:30
212.75:456:29
312.75:466:27
412.75:476:26
512.65:486:25
612.65:486:23
712.55:496:22
812.55:506:20
912.55:516:19
1012.45:516:17
1112.45:526:16
1212.45:536:14
1312.35:546:13
1412.35:546:11
1512.35:556:10
1612.25:566:09
1712.25:566:07
1812.15:576:06
1912.15:586:04
2012.15:596:03
2112.05:596:01
2212.06:006:00
2312.06:015:58
2411.96:025:57
2511.96:025:55
2611.86:035:54
2711.86:045:52
2811.86:055:51
2911.76:055:49
3011.76:065:48

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.17 kWh/m².

For context, solar energy here swings from a low near 2.24 kWh/m² to a high of 5.56 kWh/m² in May across the year — September's 4.17 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.6Bright
24.6Bright
34.5Bright
44.5Bright
54.5Bright
64.5Bright
74.4Bright
84.4Bright
94.4Bright
104.3Bright
114.3Bright
124.3Bright
134.3Bright
144.2Bright
154.2Bright
164.2Bright
174.2Bright
184.1Bright
194.1Bright
204.1Bright
214.1Bright
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 Kōzan

In seasonPeak

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

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

Kōzan's rainy season runs March–October, 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 Kōzan?

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
6.5
Beach & pool
1st-best month of the year

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

What to pack for Kōzan in September

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

In September, Kōzan sees daytime highs around 28°C and nights near 20°C. Pack light clothes. Worth having: rain gear. About 11 days see rain.

light clothesrain gear

Sea temperature near Kōzan in September

The nearest coast averages about 27°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 38 km away) is warmest in August at about 27°C and coldest in February near 13°C.

It's comfortable for a long swim from Jun 3 to Nov 12 — about 5.4 months when the water holds above 20°C.

10°15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan14Bracing
Feb13Bracing
Mar13Bracing
Apr15Cool
May18Cool
Jun22Refreshing
Jul25Warm
Aug27Warm
Sep27Warm
Oct23Refreshing
Nov20Cool
Dec16Cool

UV index in Kōzan 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 Kōzan peaks around July 15 at about 10 (extreme) — 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 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highModerateJul 15UV 10Dec 22UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5High
Apr7Very high
May8Very high
Jun10Very high
Jul10Extreme
Aug9Very high
Sep9Very high
Oct6High
Nov4Moderate
Dec3Moderate

Air quality in Kōzan 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 Kōzan is worst in April — around 22 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (October, 11 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1322 µg/m³Oct 1711 µg/m³
PM2.5 (µg/m³)Level
Jan14Moderate
Feb17Moderate
Mar21Moderate
Apr22Moderate
May20Moderate
Jun18Moderate
Jul14Moderate
Aug14Moderate
Sep12Good
Oct11Good
Nov12Good
Dec11Good
Location & terrain

Where is Kōzan?

Kōzan sits at 34.6°N, 133.1°E, 337 m above sea level, in Japan. The nearest listed city is Fuchūchō, 17 km away.

Topography around Kōzan

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

Within 3 km, the terrain around Kōzan has significant variations in elevation — a maximum elevation change of 315 m around an average of 432 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 710 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,264 m.

The land around Kōzan is covered by trees (72%) within 3 km, trees (85%) within 16 km, and trees (68%) and water (22%) within 80 km.

3 km
315 m
16 km
710 m
80 km
1,264 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Fuchūchō 17 km · Mihara 21 km · Shin’ichi 21 km · Onomichi 23 km · Shōbara 30 km · Takehara 30 km · Miyoshi 30 km · Fukuyama 31 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 Kōzan (34.5833°, 133.05°, elevation 337 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).