Tomioka weather in September

In September, Tomioka sees average daytime highs of 25°C and overnight lows near 18°C, with 257 mm of rain across 19.8 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 27°C in the first days to 22°C by the end. The sky is clear or mostly clear about 20% 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 Tomioka's 10th-clearest and 10th-windiest month. For the whole year in context, see Tomioka's year-round climate.

Daytime high
25°
3rd warmest
Overnight low
18°
10th coldest
Rainfall
257 mm
19.8 wet days
Daylight
12 h 12 min
5:32 AM – 5:46 PM
Cloud cover
70%
10th clearest
Wind
5 km/h
10th windiest
Solar energy
3.66 kWh/m²
Travel score
5.1
out of 10

Tomioka is city in Gunma Prefecture, Japan.

Density
390/km²
people per km²
Founded
1954

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 27°C in the first days to 22°C by the end.

A typical September day in Tomioka reaches about 25°C in the afternoon and slips back to 18°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 20°C and 29°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

10°15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12721
22721
32721
42721
52720
62620
72620
82620
92620
102620
112619
122619
132519
142519
152519
162518
172518
182418
192418
202418
212417
222417
232317
242317
252317
262316
272316
282216
292216
302216

How September really feels in Tomioka

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.

Tomioka 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 daysSnow daysDaylight (hours)Travel score
Jan / -1°688.53.89.81.4
Feb / -0°719.64.110.61.6
Mar12° / 13114.43.311.73.0
Apr17° / 14814.70.412.94.9
May22° / 13°17816013.95.6
Jun24° / 17°23920.7014.44.9
Jul28° / 21°28823.2014.24.2
Aug29° / 22°22522.1013.44.1
Sep25° / 18°25719.8012.25.1
Oct20° / 12°22516.9011.15.3
Nov15° / 859.90.110.14.6
Dec10° / 618.31.19.62.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 20% 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 66%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13466
23466
33367
43367
53367
63367
73466
83367
93367
103367
113367
123268
133268
143268
153367
163367
173268
183268
193367
203367
213367
223466
233466
243565
253565
263664
273664
283664
293664
303664

Chance of precipitation in September

Any precipitation

Tomioka gets around 257 mm of rain over 19.8 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 67% and peaks near 73% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
173
273
373
473
572
672
772
871
971
1070
1170
1269
1368
1468
1567
1666
1765
1865
1964
2063
2163
2262
2362
2461
2561
2661
2760
2860
2960
3060

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 45% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1041843341
2041843331
3151944311
4151944301
5162044291
6172044271
7182143260
8292243240
92102342220
103112341210
113122441190
124142539180
135152638160
146162737140
157172835130
168182934110
1710193032100
181120313080
191321312870
201422322660
211623322450
221724332240
231925331940
242026331730
252228331520
262329321420
272430321220
282632311010
29273330910
30293429810

Wind in September

Winds average 5 km/h in September.

Across September, daily wind ranges from about 5 km/h on the calmest days to 5 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm

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 5:20 AM to 5:43 AM, and sunset from 6:08 PM to 5:24 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:206:08
212.85:216:07
312.75:216:05
412.75:226:04
512.75:236:02
612.65:246:01
712.65:255:59
812.55:255:58
912.55:265:56
1012.55:275:55
1112.45:285:53
1212.45:295:52
1312.35:305:50
1412.35:305:49
1512.35:315:47
1612.25:325:46
1712.25:335:44
1812.15:345:42
1912.15:345:41
2012.15:355:39
2112.05:365:38
2212.05:375:36
2312.05:385:35
2411.95:385:33
2511.95:395:32
2611.85:405:30
2711.85:415:29
2811.85:425:27
2911.75:435:25
3011.75:435:24

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.66 kWh/m².

For context, solar energy here swings from a low near 2.44 kWh/m² to a high of 5.31 kWh/m² in May across the year — September's 3.66 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.1Bright
24.0Bright
34.0Bright
44.0Moderate
53.9Moderate
63.9Moderate
73.9Moderate
83.9Moderate
93.8Moderate
103.8Moderate
113.8Moderate
123.7Moderate
133.7Moderate
143.7Moderate
153.6Moderate
163.6Moderate
173.6Moderate
183.5Moderate
193.5Moderate
203.5Moderate
213.5Moderate
223.5Moderate
233.4Moderate
243.4Moderate
253.4Moderate
263.4Moderate
273.3Moderate
283.3Moderate
293.3Moderate
303.3Moderate
Planning a trip in September

Hazard calendar for Tomioka

In seasonPeak

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

Tomioka's rainy season runs March–October, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Tomioka?

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

5.1
Sightseeing
3rd-best month of the year
4.4
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Tomioka for sightseeing.

What to pack for Tomioka in September

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

In September, Tomioka sees daytime highs around 25°C and nights near 18°C. Pack rain gear. Worth having: light clothes. About 20 days see rain.

rain gearlight clothes

UV index in Tomioka 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 Tomioka peaks around July 18 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJul 18UV 10Dec 23UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar6High
Apr7High
May8Very high
Jun9Very high
Jul10Very high
Aug9Very high
Sep9Very high
Oct6High
Nov3Moderate
Dec2Moderate

Air quality in Tomioka 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 Tomioka is worst in April — around 21 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (December, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1821 µg/m³Dec 1810 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar19Moderate
Apr21Moderate
May20Moderate
Jun18Moderate
Jul15Moderate
Aug14Moderate
Sep13Moderate
Oct12Moderate
Nov11Good
Dec10Good
Location & terrain

Where is Tomioka?

Tomioka sits at 36.3°N, 138.9°E, 158 m above sea level, in Japan. The nearest listed city is Yoshii, 8.0 km away.

Topography around Tomioka

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

Within 3 km, the terrain around Tomioka has only modest variations in elevation — a maximum elevation change of 162 m around an average of 178 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,454 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,854 m.

The land around Tomioka is covered by artificial surfaces (41%) and trees (33%) within 3 km, trees (68%) within 16 km, and trees (73%) within 80 km.

3 km
162 m
16 km
1,454 m
80 km
2,854 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Yoshii 8.0 km · Annaka 8.0 km · Takasaki 14 km · Fujioka 16 km · Kanekomachi 20 km · Tamamura 20 km · Kodamachō-kodamaminami 22 km · Ishigami 23 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 Tomioka (36.2541°, 138.8981°, elevation 158 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. 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).