Sasayama weather in September

In September, Sasayama sees average daytime highs of 27°C and overnight lows near 20°C, with 196 mm of rain across 12.9 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 29°C in the first days to 25°C by the end. The sky is clear or mostly clear about 27% of the time in September, and the air most often feels humid.

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 Sasayama's 7th-clearest and 5th-windiest month. For the whole year in context, see Sasayama's year-round climate.

Daytime high
27°
3rd warmest
Overnight low
20°
10th coldest
Rainfall
196 mm
12.9 wet days
Daylight
12 h 12 min
5:47 AM – 6:00 PM
Cloud cover
64%
7th clearest
Wind
10 km/h
5th windiest
Solar energy
4.12 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 29°C in the first days to 25°C by the end.

A typical September day in Sasayama 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
62921
72921
82821
92821
102821
112821
122820
132720
142720
152720
162720
172719
182719
192619
202619
212619
222618
232618
242518
252518
262518
272517
282517
292417
302417

How September really feels in Sasayama

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.

Sasayama 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 / 5571.49.91.2
Feb / 648.11.810.71.6
Mar12° / 11211.70.511.73.2
Apr18° / 12510.9012.95.5
May22° / 14°14711.1013.86.4
Jun26° / 18°18614.1014.35.7
Jul29° / 23°22116.6014.14.4
Aug31° / 23°13413.9013.34.1
Sep27° / 20°19612.9012.25.8
Oct21° / 14°1549.2011.16.7
Nov16° / 787010.25.2
Dec10° / 6270.69.72.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 27% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 56%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14357
24357
34357
44357
54357
64456
74456
84357
94357
104456
114456
124456
134456
144456
154456
164357
174357
184357
194357
204258
214258
224357
234258
244456
254456
264456
274456
284456
294654
304654

Chance of precipitation in September

Any precipitation

Sasayama gets around 196 mm of rain over 12.9 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 43% and peaks near 45% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
145
245
345
445
545
645
745
845
945
1045
1145
1244
1344
1444
1543
1643
1742
1842
1942
2041
2141
2241
2340
2440
2540
2640
2739
2839
2939
3039

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the humid band about 27% of days. Sticky, muggy-or-worse air turns up on roughly 49% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1031632462
2031733461
3041832441
4042032421
5152132411
6162232391
7162331381
8172431361
9282531340
10292631320
11392730300
123102830280
134122929260
145132929240
156143028220
167153027200
178163127180
189173126160
1910193225140
2011203224130
2113213223110
2214233222100
231524312180
241625312070
251726311960
261827311850
271928301750
282029301640
292230291530
302331291430

Wind in September

Winds average 10 km/h in September.

Across September, daily wind ranges from about 9 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
19calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
1010calm
1110calm
1210calm
1310calm
1410calm
1510calm
1610calm
1710calm
1810calm
1910calm
2010calm
2110calm
2210calm
2310calm
2410calm
2510calm
2610calm
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 5:36 AM to 5:58 AM, and sunset from 6:22 PM to 5:39 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:366:22
212.75:366:21
312.75:376:19
412.75:386:18
512.65:396:16
612.65:396:15
712.65:406:13
812.55:416:12
912.55:426:10
1012.45:426:09
1112.45:436:07
1212.45:446:06
1312.35:456:04
1412.35:456:03
1512.35:466:01
1612.25:476:00
1712.25:485:58
1812.15:485:57
1912.15:495:55
2012.15:505:54
2112.05:515:52
2212.05:525:51
2312.05:525:49
2411.95:535:48
2511.95:545:46
2611.85:555:45
2711.85:555:44
2811.85:565:42
2911.75:575:41
3011.75:585:39

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.12 kWh/m².

For context, solar energy here swings from a low near 2.3 kWh/m² to a high of 5.48 kWh/m² in May across the year — September's 4.12 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
124.3Bright
134.2Bright
144.2Bright
154.2Bright
164.1Bright
174.1Bright
184.1Bright
194.0Bright
204.0Bright
214.0Moderate
223.9Moderate
233.9Moderate
243.9Moderate
253.9Moderate
263.8Moderate
273.8Moderate
283.8Moderate
293.7Moderate
303.7Moderate
Planning a trip in September

Hazard calendar for Sasayama

In seasonPeak

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

Sasayama 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 Sasayama?

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
6.0
Beach & pool
1st-best month of the year

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

What to pack for Sasayama in September

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

In September, Sasayama sees daytime highs around 27°C and nights near 20°C. Worth packing: light clothes and rain gear. About 13 days see rain.

light clothesrain gear

Sea temperature near Sasayama 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 50 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 Jun 6 to Nov 12 — about 5.3 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
Jun21Refreshing
Jul25Warm
Aug27Warm
Sep26Warm
Oct23Refreshing
Nov20Cool
Dec17Cool

UV index in Sasayama 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 Sasayama peaks around July 15 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 3 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highVery highModerateJul 15UV 10Jan 1UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5High
Apr7High
May8Very high
Jun10Very high
Jul10Extreme
Aug9Very high
Sep9Very high
Oct6High
Nov3Moderate
Dec3Moderate

Air quality in Sasayama 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 Sasayama is worst in April — around 22 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (October, 11 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1622 µg/m³Oct 1811 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb16Moderate
Mar21Moderate
Apr22Moderate
May21Moderate
Jun18Moderate
Jul17Moderate
Aug17Moderate
Sep13Moderate
Oct11Good
Nov12Moderate
Dec12Good
Location & terrain

Where is Sasayama?

Sasayama sits at 35.1°N, 135.2°E, 202 m above sea level, in Japan. The nearest listed city is Tamba-Sasayama, 1.0 km away.

Topography around Sasayama

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

Within 3 km, the terrain around Sasayama has significant variations in elevation — a maximum elevation change of 277 m around an average of 243 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 715 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,488 m.

The land around Sasayama is covered by trees (46%) and cropland (33%) within 3 km, trees (84%) within 16 km, and trees (60%) and water (21%) within 80 km.

3 km
277 m
16 km
715 m
80 km
1,488 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Tamba-Sasayama 1.0 km · Tanba 19 km · Sandachō 20 km · Tamba 21 km · Katō 24 km · Nishiwaki 24 km · Kimokawa 25 km · Nantan 25 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 Sasayama (35.0667°, 135.2167°, elevation 202 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).