Ōshū weather in September

In September, Ōshū sees average daytime highs of 22°C and overnight lows near 15°C, with 151 mm of rain across 13.5 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 3rd-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 17% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Ōshū's 9th-clearest and 9th-windiest month. For the whole year in context, see Ōshū's year-round climate.

Daytime high
22°
3rd warmest
Overnight low
15°
10th coldest
Rainfall
151 mm
13.5 wet days
Daylight
12 h 18 min
5:22 AM – 5:37 PM
Cloud cover
72%
9th clearest
Wind
7 km/h
9th windiest
Solar energy
3.53 kWh/m²
Travel score
5.8
out of 10

Ōshū is city in Iwate Prefecture, Japan.

Density
114/km²
people per km²
Founded
2006

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 25°C in the first days to 20°C by the end.

A typical September day in Ōshū 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 19°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
42518
52418
62417
72417
82417
92417
102417
112316
122316
132316
142316
152315
162215
172215
182215
192214
202214
212114
222113
232113
242113
252113
262012
272012
282012
292012
302011

How September really feels in Ōshū

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.

Ōshū 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 / -7°5810.7129.60.0
Feb / -7°5310.19.710.50.0
Mar / -3°9213.28.211.70.6
Apr13° / 9813.42.2133.3
May18° / 11012.5014.15.4
Jun21° / 14°12312.9014.75.7
Jul25° / 18°16616.5014.55.5
Aug26° / 19°15315.2013.55.6
Sep22° / 15°15113.5012.35.8
Oct17° / 12011.20115.0
Nov10° / 7311.72.29.92.2
Dec / -3°6812.48.89.30.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 17% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 69%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
12773
22773
32872
42872
52872
62971
72971
83070
93070
103070
113070
123070
133169
143169
153169
163268
173268
183169
193169
203268
213268
223268
233367
243466
253466
263466
273565
283565
293664
303664

Chance of precipitation in September

Any precipitation

Ōshū gets around 151 mm of rain over 13.5 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 46% and peaks near 51% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
149
250
350
450
550
650
751
851
951
1051
1150
1250
1350
1449
1548
1648
1747
1846
1945
2044
2143
2242
2341
2440
2540
2639
2739
2838
2938
3038

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 26% of days. Sticky, muggy-or-worse air turns up on roughly 23% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1317333115
2318333115
3419333114
4419343013
5520343012
6521342911
7621342810
882234279
992334268
10112333258
11122433247
12142532236
13162631216
14182730205
15212729184
16232828174
17262926153
18292925143
19323024123
20353022112
21373021102
2240301982
2343301872
2446311661
2548301551
2650301451
2752301341
2855291231
2958281130
3060281020

Wind in September

Winds average 7 km/h in September.

Across September, daily wind ranges from about 7 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
258calm
268calm
278calm
288calm
298calm
308calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over September. Sunrise moves from 5:08 AM to 5:35 AM, and sunset from 6:02 PM to 5:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:086:02
212.95:096:00
312.85:105:59
412.85:115:57
512.75:125:55
612.75:135:54
712.65:145:52
812.65:155:51
912.65:165:49
1012.55:165:47
1112.55:175:46
1212.45:185:44
1312.45:195:42
1412.35:205:41
1512.35:215:39
1612.35:225:37
1712.25:235:36
1812.25:245:34
1912.15:255:32
2012.15:265:30
2112.05:275:29
2212.05:285:27
2311.95:295:25
2411.95:305:24
2511.95:315:22
2611.85:325:20
2711.85:335:19
2811.75:345:17
2911.75:345:15
3011.65:355:14

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.53 kWh/m².

For context, solar energy here swings from a low near 1.98 kWh/m² to a high of 5.24 kWh/m² in May across the year — September's 3.53 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.8Moderate
23.8Moderate
33.7Moderate
43.7Moderate
53.7Moderate
63.7Moderate
73.6Moderate
83.6Moderate
93.6Moderate
103.6Moderate
113.6Moderate
123.5Moderate
133.5Moderate
143.5Moderate
153.5Moderate
163.5Moderate
173.5Moderate
183.5Moderate
193.5Moderate
203.4Moderate
213.4Moderate
223.4Moderate
233.4Moderate
243.4Moderate
253.4Moderate
263.4Moderate
273.4Moderate
283.3Moderate
293.3Moderate
303.3Moderate
Planning a trip in September

Hazard calendar for Ōshū

In seasonPeak

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

Ōshū 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 Ōshū?

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

5.8
Sightseeing
1st-best month of the year
4.2
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Ōshū for sightseeing.

What to pack for Ōshū in September

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

In September, Ōshū sees daytime highs around 22°C and nights near 15°C. Pack rain gear. Worth having: light clothes. About 14 days see rain.

rain gearlight clothes

Sea temperature near Ōshū in September

The nearest coast averages about 22°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 49 km away) is warmest in August at about 22°C and coldest in March near 7°C.

It's comfortable for a long swim from Jul 21 to Oct 3 — about 2.5 months when the water holds above 20°C.

5°10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan11Bracing
Feb8Bracing
Mar7Bracing
Apr9Bracing
May12Bracing
Jun17Cool
Jul20Cool
Aug22Refreshing
Sep22Refreshing
Oct19Cool
Nov16Cool
Dec13Bracing

UV index in Ōshū in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Ōshū peaks around August 19 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighVery highHighModerateLowAug 19UV 9Jan 1UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun8Very high
Jul6High
Aug9Very high
Sep7Very high
Oct5Moderate
Nov3Moderate
Dec2Low

Air quality in Ōshū 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 Ōshū is worst in April — around 20 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (December, 9 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1620 µg/m³Dec 1710 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb14Moderate
Mar19Moderate
Apr20Moderate
May19Moderate
Jun14Moderate
Jul12Moderate
Aug11Good
Sep11Good
Oct11Good
Nov11Good
Dec9Good
Location & terrain

Where is Ōshū?

Ōshū sits at 39.1°N, 141.2°E, 36 m above sea level, in Japan. The nearest listed city is Mizusawa, 3.0 km away.

Topography around Ōshū

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

Within 3 km, the terrain around Ōshū has only modest variations in elevation — a maximum elevation change of 104 m around an average of 45 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 767 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,007 m.

The land around Ōshū is covered by artificial surfaces (38%), cropland (32%) and trees (23%) within 3 km, trees (59%) and cropland (30%) within 16 km, and trees (71%) within 80 km.

3 km
104 m
16 km
767 m
80 km
2,007 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Mizusawa 3.0 km · Kanegasaki 8.0 km · Kitakami 17 km · Ichinoseki 25 km · Hanamaki 27 km · Tōno 37 km · Rikuzen-Takata 44 km · Kesennuma 44 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 Ōshū (39.1393°, 141.1685°, elevation 36 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).