Nanyō weather in September

In September, Nanyō sees average daytime highs of 22°C and overnight lows near 15°C, with 155 mm of rain across 15.3 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 25°C in the first days to 20°C by the end. The sky is clear or mostly clear about 14% of the time in September, and the air most often feels humid.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Nanyō's 6th-clearest and 10th-windiest month. For the whole year in context, see Nanyō's year-round climate.

Daytime high
22°
3rd warmest
Overnight low
15°
10th coldest
Rainfall
155 mm
15.3 wet days
Daylight
12 h 12 min
5:27 AM – 5:41 PM
Cloud cover
72%
6th clearest
Wind
7 km/h
10th windiest
Solar energy
3.57 kWh/m²
Travel score
5.5
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 25°C in the first days to 20°C by the end.

A typical September day in Nanyō reaches about 22°C in the afternoon and slips back to 15°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 18°C and 26°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°151015202530
Avg high (°C)Avg low (°C)
12518
22518
32518
42418
52418
62417
72417
82417
92417
102317
112316
122316
132316
142316
152216
162215
172215
182215
192215
202114
212114
222114
232114
242013
252013
262013
272013
282012
291912
301912

How September really feels in Nanyō

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.

Nanyō weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -5°19024.425.29.70.0
Feb / -5°13720.620.510.50.0
Mar / -2°14619.415.611.70.2
Apr11° / 11515.14.4132.5
May18° / 11614.20.1145.1
Jun22° / 14°15515.2014.65.4
Jul25° / 18°24119.9014.45.1
Aug26° / 19°18317.4013.55.4
Sep22° / 15°15515.3012.35.5
Oct16° / 13914.30.1114.5
Nov10° / 13417.55.59.91.7
Dec / -3°18123.219.29.40.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 14% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 68%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13367
23367
33268
43268
53367
63367
73367
83367
93367
103367
113367
123268
133268
143268
153367
163268
173169
183070
193169
203169
213070
223070
233169
243070
253070
263070
273169
282971
292971
302971

Chance of precipitation in September

Any precipitation

Nanyō gets around 155 mm of rain over 15.3 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.

0%20%40%60%151015202530
Rain chance (%)
155
255
355
455
555
655
755
855
955
1054
1154
1254
1353
1453
1552
1652
1751
1851
1950
2050
2149
2249
2349
2449
2549
2650
2750
2850
2951
3050

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the humid band about 27% of days. Sticky, muggy-or-worse air turns up on roughly 24% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1212344110
221335419
331435408
431536397
531636387
641836376
751936355
862036345
972135324
1092235314
11102334293
12122434273
13142533252
14162632242
15192731222
16212830201
17242929181
18263027161
19293026141
20323124131
21343123111
22373221100
2340321980
2442321870
2545331760
2647331550
2749331440
2852321330
2954321220
3056311120

Wind in September

Winds average 7 km/h in September.

Across September, daily wind ranges from about 6 km/h on the calmest days to 7 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 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 72 minutes over September. Sunrise moves from 5:13 AM to 5:39 AM, and sunset from 6:05 PM to 5:18 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:136:05
212.85:146:04
312.85:156:02
412.75:166:00
512.75:175:59
612.75:185:57
712.65:195:56
812.65:205:54
912.55:205:52
1012.55:215:51
1112.55:225:49
1212.45:235:48
1312.45:245:46
1412.35:255:44
1512.35:265:43
1612.25:275:41
1712.25:285:39
1812.25:285:38
1912.15:295:36
2012.15:305:35
2112.05:315:33
2212.05:325:31
2311.95:335:30
2411.95:345:28
2511.95:355:26
2611.85:365:25
2711.85:365:23
2811.75:375:22
2911.75:385:20
3011.75:395:18

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.57 kWh/m².

For context, solar energy here swings from a low near 1.82 kWh/m² to a high of 5.35 kWh/m² in May across the year — September's 3.57 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
14.0Moderate
23.9Moderate
33.9Moderate
43.9Moderate
53.8Moderate
63.8Moderate
73.8Moderate
83.7Moderate
93.7Moderate
103.7Moderate
113.6Moderate
123.6Moderate
133.6Moderate
143.6Moderate
153.5Moderate
163.5Moderate
173.5Moderate
183.5Moderate
193.4Moderate
203.4Moderate
213.4Moderate
223.4Moderate
233.3Moderate
243.3Moderate
253.3Moderate
263.3Moderate
273.3Moderate
283.2Moderate
293.2Moderate
303.2Moderate
Planning a trip in September

Is September a good time to visit Nanyō?

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

5.5
Sightseeing
1st-best month of the year
3.9
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Nanyō for sightseeing.

What to pack for Nanyō in September

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

In September, Nanyō sees daytime highs around 22°C and nights near 15°C. Pack rain gear. Worth having: light clothes. About 15 days see rain.

rain gearlight clothes

Sea temperature near Nanyō in September

The nearest coast averages about 25°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 65 km away) is warmest in August at about 26°C and coldest in March near 9°C.

It's comfortable for a long swim from Jun 21 to Oct 29 — about 4.3 months when the water holds above 20°C.

10°20°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan12Bracing
Feb10Bracing
Mar9Bracing
Apr11Bracing
May15Bracing
Jun20Cool
Jul23Refreshing
Aug26Warm
Sep25Warm
Oct22Refreshing
Nov18Cool
Dec15Bracing

UV index in Nanyō in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 8 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Nanyō peaks around August 12 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateAug 12UV 10Jan 1UV 2
UV index (midday)Level
Jan2Moderate
Feb3Moderate
Mar5Moderate
Apr7High
May8Very high
Jun8Very high
Jul9Very high
Aug10Very high
Sep8Very high
Oct5High
Nov3Moderate
Dec2Moderate

Air quality in Nanyō 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 Nanyō is worst in April — around 22 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (December, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1622 µg/m³Dec 1710 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar21Moderate
Apr22Moderate
May21Moderate
Jun16Moderate
Jul14Moderate
Aug12Moderate
Sep12Good
Oct12Good
Nov11Good
Dec10Good
Location & terrain

Where is Nanyō?

Nanyō sits at 38.0°N, 140.1°E, 212 m above sea level, in Japan. The nearest listed city is Takahata, 8.0 km away.

Topography around Nanyō

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

Within 3 km, the terrain around Nanyō has only modest variations in elevation — a maximum elevation change of 199 m around an average of 222 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 803 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,110 m.

The land around Nanyō is covered by cropland (61%) and trees (21%) within 3 km, trees (61%) and cropland (29%) within 16 km, and trees (77%) within 80 km.

3 km
199 m
16 km
803 m
80 km
2,110 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Takahata 8.0 km · Nagai 10 km · Yonezawa 15 km · Kaminoyama 19 km · Yamagata 31 km · Sagae 39 km · Tendō 41 km · Date 42 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 Nanyō (38.0432°, 140.1128°, elevation 212 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. 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).