Ōmihachiman weather in September

In September, Ōmihachiman sees average daytime highs of 27°C and overnight lows near 20°C, with 179 mm of rain across 12.3 wet days and about 12.2 hours of daylight. It is the 3rd-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 29°C in the first days to 24°C by the end. The sky is clear or mostly clear about 25% 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 Ōmihachiman's 7th-clearest and 9th-windiest month. For the whole year in context, see Ōmihachiman's year-round climate.

Daytime high
27°
3rd warmest
Overnight low
20°
10th coldest
Rainfall
179 mm
12.3 wet days
Daylight
12 h 12 min
5:43 AM – 5:56 PM
Cloud cover
65%
7th clearest
Wind
9 km/h
9th windiest
Solar energy
4 kWh/m²
Travel score
5.9
out of 10

Ōmihachiman is city in Shiga Prefecture, Japan.

Density
1,068/km²
people per km²
Founded
2010

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 29°C in the first days to 24°C by the end.

A typical September day in Ōmihachiman reaches about 27°C in the afternoon and slips back to 20°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 23°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)
12922
22922
32922
42922
52922
62821
72821
82821
92821
102821
112721
122720
132720
142720
152720
162620
172619
182619
192619
202619
212519
222518
232518
242518
252518
262418
272417
282417
292417
302417

How September really feels in Ōmihachiman

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.

Ōmihachiman 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 / 8113.97.59.90.7
Feb / 7612.76.510.71.0
Mar12° / 11613.52.111.72.7
Apr17° / 12311.60.112.95.1
May22° / 13°14811.6013.86.3
Jun25° / 18°18614014.35.7
Jul29° / 22°21015.9014.14.5
Aug31° / 23°12212.4013.34.3
Sep27° / 20°17912.3012.25.9
Oct21° / 14°15210.8011.16.4
Nov15° / 819010.24.7
Dec / 7511.63.19.72.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 25% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 59%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14159
24159
34258
44159
54159
64258
74258
84258
94258
104258
114258
124258
134258
144258
154258
164159
174159
184060
194159
204060
214159
224060
234060
244060
253961
264060
274159
284060
294060
304060

Chance of precipitation in September

Any precipitation

Ōmihachiman gets around 179 mm of rain over 12.3 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 41% and peaks near 44% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
142
242
343
443
543
643
743
844
944
1044
1144
1243
1343
1443
1542
1642
1741
1841
1941
2040
2140
2240
2339
2439
2539
2639
2739
2839
2939
3039

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 29% of days. Sticky, muggy-or-worse air turns up on roughly 50% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1031540411
2031640401
3041740381
4041840371
5141940361
6152039341
7152238331
8162338310
9172537300
10272636290
11282735270
12292935260
133103033240
144113132220
154123231200
165133330190
176153329170
187163428150
198173427140
209193426120
2110203425110
221122342390
231223342280
241324342170
251525342060
261627341850
271728341740
281929331640
292029331530
302130321330

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 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
18calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
109calm
119calm
129calm
139calm
149calm
159calm
169calm
179calm
189calm
199calm
209calm
219calm
229calm
239calm
249calm
259calm
269calm
279calm
289calm
299calm
309calm

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 5:32 AM to 5:54 AM, and sunset from 6:19 PM to 5:36 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:326:19
212.75:336:17
312.75:346:16
412.75:346:14
512.65:356:13
612.65:366:11
712.65:376:10
812.55:376:08
912.55:386:07
1012.45:396:05
1112.45:406:04
1212.45:406:02
1312.35:416:01
1412.35:425:59
1512.35:435:58
1612.25:435:56
1712.25:445:55
1812.15:455:53
1912.15:465:52
2012.15:465:50
2112.05:475:49
2212.05:485:47
2312.05:495:46
2411.95:505:44
2511.95:505:43
2611.85:515:41
2711.85:525:40
2811.85:535:39
2911.75:535:37
3011.75:545:36

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4 kWh/m².

For context, solar energy here swings from a low near 2.15 kWh/m² to a high of 5.32 kWh/m² in May across the year — September's 4 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.5Bright
24.5Bright
34.5Bright
44.4Bright
54.4Bright
64.3Bright
74.3Bright
84.3Bright
94.2Bright
104.2Bright
114.1Bright
124.1Bright
134.1Bright
144.0Bright
154.0Bright
164.0Moderate
174.0Moderate
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 Ōmihachiman

In seasonPeak

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

Ōmihachiman 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 Ōmihachiman?

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

5.9
Sightseeing
3rd-best month of the year
6.0
Beach & pool
2nd-best month of the year

September is a reasonable time to visit Ōmihachiman for sightseeing.

What to pack for Ōmihachiman in September

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

In September, Ōmihachiman sees daytime highs around 27°C and nights near 20°C. Worth packing: light clothes and rain gear. About 12 days see rain.

light clothesrain gear

Sea temperature near Ōmihachiman in September

The nearest coast averages about 26°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 56 km away) is warmest in August at about 27°C and coldest in February near 13°C.

It's comfortable for a long swim from May 31 to Nov 9 — about 5.4 months when the water holds above 20°C.

10°15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan14Bracing
Feb13Bracing
Mar14Bracing
Apr15Cool
May18Cool
Jun22Refreshing
Jul26Warm
Aug27Warm
Sep26Warm
Oct22Refreshing
Nov19Cool
Dec16Cool

UV index in Ōmihachiman 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 Ōmihachiman peaks around July 14 at about 10 (extreme) — 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 highVery highModerateJul 14UV 10Dec 23UV 2
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5High
Apr7High
May8Very high
Jun10Very high
Jul10Extreme
Aug9Very high
Sep9Very high
Oct6High
Nov3Moderate
Dec2Moderate

Air quality in Ōmihachiman 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 Ōmihachiman is worst in April — around 24 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (October, 12 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateApr 1723 µg/m³Oct 1812 µg/m³
PM2.5 (µg/m³)Level
Jan14Moderate
Feb17Moderate
Mar22Moderate
Apr24Moderate
May22Moderate
Jun19Moderate
Jul17Moderate
Aug17Moderate
Sep14Moderate
Oct12Good
Nov13Moderate
Dec12Moderate
Location & terrain

Where is Ōmihachiman?

Ōmihachiman sits at 35.1°N, 136.1°E, 91 m above sea level, in Japan. The nearest listed city is Yasu, 8.0 km away.

Topography around Ōmihachiman

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

Within 3 km, the terrain around Ōmihachiman has only modest variations in elevation — a maximum elevation change of 198 m around an average of 95 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 355 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,602 m.

The land around Ōmihachiman is covered by cropland (52%) and artificial surfaces (37%) within 3 km, cropland (31%), water (27%) and artificial surfaces (21%) within 16 km, and trees (58%) within 80 km.

3 km
198 m
16 km
355 m
80 km
1,602 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Yasu 8.0 km · Youkaichi 9.0 km · Echigawa 10 km · Moriyama 12 km · Rittō 14 km · Konan 14 km · Kitahama 17 km · Kusatsu 17 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 Ōmihachiman (35.1286°, 136.0976°, elevation 91 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).