Jōetsu weather in September

In September, Jōetsu sees average daytime highs of 26°C and overnight lows near 20°C, with 162 mm of rain across 14.1 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 7th-wettest month of the year here.

Highs ease over the month, from about 28°C in the first days to 23°C by the end. The sky is clear or mostly clear about 23% 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 Jōetsu's 6th-clearest and 9th-windiest month. For the whole year in context, see Jōetsu's year-round climate.

Daytime high
26°
3rd warmest
Overnight low
20°
10th coldest
Rainfall
162 mm
14.1 wet days
Daylight
12 h 12 min
5:34 AM – 5:48 PM
Cloud cover
66%
6th clearest
Wind
9 km/h
9th windiest
Solar energy
4.04 kWh/m²
Travel score
5.8
out of 10

Jōetsu is city in Niigata Prefecture, Japan.

Density
195/km²
people per km²
Founded
1971

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 23°C by the end.

A typical September day in Jōetsu reaches about 26°C in the afternoon and slips back to 20°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 30°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)
12822
22822
32822
42822
52822
62822
72722
82721
92721
102721
112721
122621
132621
142620
152620
162620
172520
182519
192519
202519
212519
222419
232418
242418
252418
262418
272318
282317
292317
302317

How September really feels in Jōetsu

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.

Jōetsu weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 25325.916.39.70.2
Feb / 17821.213.310.60.3
Mar10° / 14519.66.511.71.6
Apr15° / 9713.40.412.94.3
May20° / 13°9211.60146.1
Jun24° / 18°11511.5014.56.4
Jul28° / 22°19114.4014.35.3
Aug30° / 24°12212.1013.44.9
Sep26° / 20°16214.1012.35.8
Oct20° / 14°16415.10115.6
Nov14° / 18018.50.3103.4
Dec / 24724.28.49.51.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 23% 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 60%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14258
24258
34258
44258
54258
64258
74159
84258
94258
104159
114258
124258
134159
144258
154159
164060
174060
184060
194060
204060
213961
223961
233862
243862
253862
263862
273862
283862
293763
303862

Chance of precipitation in September

Any precipitation

Jōetsu gets around 162 mm of rain over 14.1 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 48% and peaks near 50% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
147
247
348
448
549
649
749
850
950
1050
1150
1250
1350
1449
1549
1649
1748
1848
1948
2047
2147
2247
2347
2447
2547
2647
2747
2847
2948
3048

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 31% 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 (%)
1021240443
2021341423
3021441402
4021541392
5031741372
6131841352
7141941342
8142140322
9152240302
10162340282
11272539261
12282638241
13392737231
143102936211
154123034191
165133133171
176153231151
187163330140
198183429120
209193527100
211021352690
221122352470
231224362260
241325362050
251427361940
261528371740
271629361530
281730361420
291931361320
302032351120

Wind in September

Winds average 9 km/h in September.

Across September, daily wind ranges from about 8 km/h on the calmest days to 10 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
99calm
109calm
119calm
129calm
139calm
149calm
159calm
169calm
179calm
189calm
199calm
209calm
219calm
229calm
239calm
249calm
259calm
269calm
2710calm
2810calm
2910calm
3010calm

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 5:22 AM to 5:46 AM, and sunset from 6:12 PM to 5:26 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:226:12
212.85:236:10
312.85:236:09
412.75:246:07
512.75:256:06
612.65:266:04
712.65:276:03
812.65:286:01
912.55:285:59
1012.55:295:58
1112.45:305:56
1212.45:315:55
1312.45:325:53
1412.35:335:52
1512.35:345:50
1612.25:345:48
1712.25:355:47
1812.25:365:45
1912.15:375:44
2012.15:385:42
2112.05:395:40
2212.05:395:39
2311.95:405:37
2411.95:415:36
2511.95:425:34
2611.85:435:33
2711.85:445:31
2811.75:455:29
2911.75:465:28
3011.75:465:26

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.04 kWh/m².

For context, solar energy here swings from a low near 1.89 kWh/m² to a high of 5.79 kWh/m² in May across the year — September's 4.04 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.6Bright
24.5Bright
34.5Bright
44.5Bright
54.4Bright
64.4Bright
74.3Bright
84.3Bright
94.2Bright
104.2Bright
114.2Bright
124.1Bright
134.1Bright
144.0Bright
154.0Bright
164.0Moderate
173.9Moderate
183.9Moderate
193.9Moderate
203.9Moderate
213.8Moderate
223.8Moderate
233.8Moderate
243.8Moderate
253.7Moderate
263.7Moderate
273.7Moderate
283.6Moderate
293.6Moderate
303.6Moderate
Planning a trip in September

Hazard calendar for Jōetsu

In seasonPeak

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

Jōetsu 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 Jōetsu?

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

5.8
Sightseeing
3rd-best month of the year
5.5
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Jōetsu for sightseeing.

What to pack for Jōetsu in September

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

In September, Jōetsu sees daytime highs around 26°C and nights near 20°C. Pack rain gear. Worth having: light clothes. About 14 days see rain.

rain gearlight clothes

Sea temperature near Jōetsu 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 offshore is warmest in August at about 27°C and coldest in March near 10°C.

It's comfortable for a long swim from Jun 20 to Nov 1 — about 4.4 months when the water holds above 20°C.

10°20°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan13Bracing
Feb11Bracing
Mar10Bracing
Apr11Bracing
May15Bracing
Jun20Cool
Jul23Refreshing
Aug27Warm
Sep25Warm
Oct22Refreshing
Nov19Cool
Dec15Cool

UV index in Jōetsu 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 Jōetsu 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
Feb4Moderate
Mar4Moderate
Apr7High
May8Very high
Jun9Very high
Jul9Very high
Aug10Very high
Sep9Very high
Oct5High
Nov3Moderate
Dec2Moderate

Air quality in Jōetsu 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 Jōetsu is worst in April — around 22 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (December, 9 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1521 µg/m³Dec 149 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar20Moderate
Apr22Moderate
May20Moderate
Jun17Moderate
Jul15Moderate
Aug12Good
Sep10Good
Oct10Good
Nov10Good
Dec9Good
Location & terrain

Where is Jōetsu?

Jōetsu sits at 37.1°N, 138.2°E, 10 m above sea level, in Japan. The nearest listed city is Myoko, 14 km away.

Topography around Jōetsu

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

Within 3 km, the terrain around Jōetsu has only modest variations in elevation — a maximum elevation change of 177 m around an average of 22 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,200 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,900 m.

The land around Jōetsu is covered by artificial surfaces (46%), trees (24%) and cropland (20%) within 3 km, trees (39%) and water (32%) within 16 km, and trees (53%) and water (37%) within 80 km.

3 km
177 m
16 km
1,200 m
80 km
2,900 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Myoko 14 km · Arai 16 km · Iiyama 35 km · Itoigawa 37 km · Kashiwazaki 37 km · Nakano 46 km · Tōkamachi 47 km · Ojiya 53 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 Jōetsu (37.1483°, 138.2364°, elevation 10 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).