Yakushima weather in September

In September, Yakushima sees average daytime highs of 27°C and overnight lows near 25°C, with 237 mm of rain across 15.8 wet days and about 12.2 hours of daylight. It is the 3rd-warmest and 2nd-wettest month of the year here.

Highs ease over the month, from about 28°C in the first days to 26°C by the end. The sky is clear or mostly clear about 37% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 36 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Yakushima's 3rd-clearest and 8th-windiest month. For the whole year in context, see Yakushima's year-round climate.

Daytime high
27°
3rd warmest
Overnight low
25°
10th coldest
Rainfall
237 mm
15.8 wet days
Daylight
12 h 12 min
6:06 AM – 6:17 PM
Cloud cover
58%
3rd clearest
Wind
24 km/h
8th windiest
Solar energy
4.63 kWh/m²
Travel score
5.7
out of 10

Yakushima is human settlement in Japan.

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 28°C in the first days to 26°C by the end.

A typical September day in Yakushima reaches about 27°C in the afternoon and slips back to 25°C overnight — a 1°C spread between the day's warmth and the night's chill. On most days the high lands between 25°C and 28°C. Set against its neighbours, September runs about 1°C cooler than August and about 3°C warmer than October.

20°23°25°28°30°151015202530
Avg high (°C)Avg low (°C)
12826
22826
32826
42826
52826
62726
72726
82726
92726
102726
112726
122726
132726
142726
152725
162725
172725
182725
192725
202625
212625
222625
232625
242625
252625
262624
272624
282624
292624
302624

How September really feels in Yakushima

Once humidity and wind are folded in, September averages 0 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
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Yakushima weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan14° / 12°12213.110.33.8
Feb15° / 12°12612.710.94.0
Mar17° / 14°18214.611.84.8
Apr19° / 17°19012.712.75.7
May22° / 20°21012.913.56.1
Jun25° / 23°43819.613.95.1
Jul27° / 26°17312.613.85.9
Aug28° / 27°14114.713.15.4
Sep27° / 25°23715.812.25.7
Oct24° / 22°1701311.36.5
Nov20° / 18°1491210.56.1
Dec16° / 14°11411.810.14.9

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 37% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 48%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15248
25248
35248
45149
55149
65149
75050
85050
95050
105050
115149
125149
135248
145248
155248
165248
175248
185248
195248
205248
215248
225347
235347
245347
255347
265347
275347
285347
295347
305347

Chance of precipitation in September

Any precipitation

Yakushima gets around 237 mm of rain over 15.8 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 52% and peaks near 55% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
153
254
354
455
555
655
755
855
955
1054
1154
1253
1352
1452
1551
1651
1751
1851
1951
2050
2150
2250
2349
2449
2549
2648
2748
2848
2948
3048

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 41% of days. Sticky, muggy-or-worse air turns up on roughly 90% of them.

0%25%50%75%100%151015202530
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
10064054
20074152
30074251
40184349
50184347
60194446
701104544
802104543
902114541
1003124540
1103134538
1204154437
1315164435
1416174333
1517194231
1618204229
1719214127
18210224125
19211244023
20212254021
21312264020
22313263918
23314273916
24415283915
25416283913
26517283812
27518293811
2861829389
2961929378
3072029378

Wind in September

Winds average 24 km/h in September.

Across September, daily wind ranges from about 22 km/h on the calmest days to 26 km/h at its breeziest. It stays fairly steady from day to day.

0102030151015202530
Wind speed (km/h)Feels
122breezy
222breezy
322breezy
422breezy
522breezy
622breezy
722breezy
823breezy
923breezy
1023breezy
1123breezy
1223breezy
1323breezy
1423breezy
1524breezy
1624breezy
1724breezy
1824breezy
1924breezy
2024breezy
2125breezy
2225breezy
2325breezy
2425breezy
2525breezy
2625breezy
2725breezy
2825breezy
2925breezy
3026breezy

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 36 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 54 minutes over September. Sunrise moves from 5:58 AM to 6:15 AM, and sunset from 6:36 PM to 5:59 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.65:586:36
212.65:586:35
312.65:596:34
412.65:596:33
512.56:006:31
612.56:016:30
712.56:016:29
812.46:026:28
912.46:026:26
1012.46:036:25
1112.36:036:24
1212.36:046:22
1312.36:056:21
1412.26:056:20
1512.26:066:18
1612.26:066:17
1712.16:076:16
1812.16:076:15
1912.16:086:13
2012.16:096:12
2112.06:096:11
2212.06:106:09
2312.06:106:08
2411.96:116:07
2511.96:126:05
2611.96:126:04
2711.86:136:03
2811.86:136:01
2911.86:146:00
3011.76:155:59

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.63 kWh/m².

For context, solar energy here swings from a low near 2.24 kWh/m² to a high of 5.86 kWh/m² in July across the year — September's 4.63 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.1Bright
35.1Bright
45.0Bright
55.0Bright
65.0Bright
74.9Bright
84.9Bright
94.9Bright
104.8Bright
114.8Bright
124.8Bright
134.8Bright
144.7Bright
154.7Bright
164.7Bright
174.6Bright
184.6Bright
194.6Bright
204.5Bright
214.5Bright
224.5Bright
234.4Bright
244.4Bright
254.3Bright
264.3Bright
274.3Bright
284.3Bright
294.2Bright
304.2Bright
Planning a trip in September

Hazard calendar for Yakushima

In seasonPeak

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

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

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

Is September a good time to visit Yakushima?

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
5.8
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Yakushima for sightseeing.

What to pack for Yakushima in September

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

In September, Yakushima sees daytime highs around 27°C and nights near 25°C. Pack rain gear. Worth having: light clothes, sun protection and a windbreaker. About 16 days see rain.

rain gearlight clothessun protectiona windbreaker

Sea temperature near Yakushima in September

The nearest coast averages about 28°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 29°C and coldest in February near 20°C.

It's comfortable for a long swim from Feb 25 to Feb 7 — about 11.4 months when the water holds above 20°C.

20°25°30°JanFebMarAprMayJunJulAugSepOctNovDeccoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan21Refreshing
Feb20Cool
Mar20Refreshing
Apr21Refreshing
May23Refreshing
Jun25Warm
Jul28Warm
Aug29Tropical
Sep28Warm
Oct26Warm
Nov24Warm
Dec22Refreshing

UV index in Yakushima in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Yakushima peaks around June 22 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 4 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJun 22UV 11Jan 10UV 4
UV index (midday)Level
Jan4Moderate
Feb6High
Mar7Very high
Apr9Very high
May9Very high
Jun11Extreme
Jul11Extreme
Aug10Very high
Sep10Extreme
Oct7High
Nov5High
Dec4Moderate

Air quality in Yakushima 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 Yakushima is worst in April — around 21 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (July, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1420 µg/m³Jul 2010 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb16Moderate
Mar20Moderate
Apr21Moderate
May19Moderate
Jun13Moderate
Jul10Good
Aug11Good
Sep10Good
Oct10Good
Nov11Good
Dec10Good
Location & terrain

Where is Yakushima?

Yakushima sits at 30.4°N, 130.6°E, 0 m above sea level, in Japan. The nearest listed city is Nishinoomote, 51 km away.

Topography around Yakushima

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

Within 3 km, the terrain around Yakushima has large variations in elevation — a maximum elevation change of 608 m around an average of 81 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,916 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,893 m.

The land around Yakushima is covered by trees (54%) and water (44%) within 3 km, water (67%) and trees (33%) within 16 km, and water (93%) within 80 km.

3 km
608 m
16 km
1,916 m
80 km
1,893 m
treesgrasslandartificial surfaceswater
September weather nearby: Nishinoomote 51 km · Ibusuki 94 km · Makurazaki 103 km · Minamikyushu 108 km · Kanoya 112 km · Minamisatsuma 117 km · Kaseda-shirakame 119 km · Tarumizu 122 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 Yakushima (30.388°, 130.6492°, elevation 0 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).