Yasu weather in September

In September, Yasu sees average daytime highs of 28°C and overnight lows near 20°C, with 153 mm of rain across 11.5 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 30°C in the first days to 25°C by the end. The sky is clear or mostly clear about 29% 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 Yasu's 7th-clearest and 7th-windiest month. For the whole year in context, see Yasu's year-round climate.

Daytime high
28°
3rd warmest
Overnight low
20°
10th coldest
Rainfall
153 mm
11.5 wet days
Daylight
12 h 12 min
5:44 AM – 5:57 PM
Cloud cover
63%
7th clearest
Wind
9 km/h
7th windiest
Solar energy
4.1 kWh/m²
Travel score
5.8
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 30°C in the first days to 25°C by the end.

A typical September day in Yasu reaches about 28°C in the afternoon and slips back to 20°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 24°C and 31°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)
13022
23022
33022
43022
53022
62921
72921
82921
92921
102921
112921
122820
132820
142820
152820
162720
172720
182719
192719
202719
212619
222618
232618
242618
252618
262518
272517
282517
292517
302517

How September really feels in Yasu

Once humidity and wind are folded in, September averages 2 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
2
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Yasu 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 / 618.32.59.91.2
Feb / 6492.510.71.6
Mar12° / 11012.20.611.73.2
Apr18° / 11911012.95.5
May23° / 13°13810.7013.86.5
Jun26° / 18°17712.9014.35.8
Jul30° / 23°18214.8014.14.3
Aug32° / 24°10311.1013.34.0
Sep28° / 20°15311.5012.25.8
Oct22° / 13°1489.6011.16.7
Nov16° / 746.8010.25.3
Dec10° / 587.71.19.72.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 29% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 56%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14357
24357
34357
44357
54456
64456
74456
84357
94456
104456
114357
124357
134456
144456
154357
164357
174357
184357
194258
204357
214357
224357
234357
244357
254357
264456
274456
284456
294357
304456

Chance of precipitation in September

Any precipitation

Yasu gets around 153 mm of rain over 11.5 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 39% and peaks near 41% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
139
239
340
440
540
640
741
841
941
1040
1140
1240
1339
1439
1538
1638
1738
1837
1937
2037
2137
2237
2337
2437
2537
2637
2737
2837
2937
3038

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 (%)
1041338431
2141438421
3141637411
4151737391
5151837381
6152036361
7162136351
8262335331
9272435321
10282634301
11282834290
12392833270
133102932250
144123131230
154133130210
165143229200
175163328180
186173327160
197193326150
208203325130
219223324120
2210233324100
231124332390
241226332280
251327332070
261428331960
271529331850
281630331740
291831321630
301931321530

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
28calm
38calm
48calm
58calm
68calm
78calm
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 5:55 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
412.75:356:15
512.65:356:13
612.65:366:12
712.65:376:10
812.55:386:09
912.55:386:07
1012.45:396:06
1112.45:406:04
1212.45:416:03
1312.35:416:01
1412.35:426:00
1512.35:435:58
1612.25:445:57
1712.25:445:55
1812.15:455:54
1912.15:465:52
2012.15:475:51
2112.05:485:49
2212.05:485:48
2312.05:495:46
2411.95:505:45
2511.95:515:43
2611.85:515:42
2711.85:525:40
2811.85:535:39
2911.75:545:37
3011.75:555:36

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.1 kWh/m².

For context, solar energy here swings from a low near 2.23 kWh/m² to a high of 5.41 kWh/m² in May across the year — September's 4.1 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.7Bright
24.6Bright
34.6Bright
44.5Bright
54.5Bright
64.5Bright
74.4Bright
84.4Bright
94.3Bright
104.3Bright
114.3Bright
124.2Bright
134.2Bright
144.2Bright
154.1Bright
164.1Bright
174.0Bright
184.0Bright
194.0Moderate
204.0Moderate
213.9Moderate
223.9Moderate
233.9Moderate
243.8Moderate
253.8Moderate
263.8Moderate
273.7Moderate
283.7Moderate
293.7Moderate
303.6Moderate
Planning a trip in September

Hazard calendar for Yasu

In seasonPeak

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

Yasu 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 Yasu?

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
6.3
Beach & pool
2nd-best month of the year

September is a reasonable time to visit Yasu for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Yasu in September

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

In September, Yasu sees daytime highs around 28°C and nights near 20°C. Pack light clothes. Worth having: rain gear. About 12 days see rain.

light clothesrain gear

Sea temperature near Yasu 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 60 km away) is warmest in August at about 27°C and coldest in March near 11°C.

It's comfortable for a long swim from Jun 12 to Nov 7 — about 4.9 months when the water holds above 20°C.

10°15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan13Bracing
Feb12Bracing
Mar11Bracing
Apr13Bracing
May17Cool
Jun21Refreshing
Jul24Warm
Aug27Warm
Sep26Warm
Oct22Refreshing
Nov19Cool
Dec16Cool

UV index in Yasu 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 Yasu 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 Yasu 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 Yasu 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 Yasu?

Yasu sits at 35.1°N, 136.0°E, 87 m above sea level, in Japan. The nearest listed city is Moriyama, 5.0 km away.

Topography around Yasu

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

Within 3 km, the terrain around Yasu has only modest variations in elevation — a maximum elevation change of 28 m around an average of 90 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 781 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,397 m.

The land around Yasu is covered by cropland (60%) and artificial surfaces (28%) within 3 km, trees (27%), water (26%) and cropland (22%) within 16 km, and trees (58%) within 80 km.

3 km
28 m
16 km
781 m
80 km
1,397 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Moriyama 5.0 km · Ōmihachiman 8.0 km · Rittō 8.0 km · Kusatsu 10 km · Kitahama 12 km · Konan 13 km · Youkaichi 16 km · Ōtsu 18 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 Yasu (35.1005°, 136.0178°, elevation 87 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).