Yakumo weather in September

In September, Yakumo sees average daytime highs of 20°C and overnight lows near 17°C, with 176 mm of rain across 13.1 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 2nd-wettest month of the year here.

Highs ease over the month, from about 22°C in the first days to 18°C by the end. The sky is clear or mostly clear about 28% of the time in September, and the air most often feels comfortable.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Yakumo's 4th-clearest and 9th-windiest month. For the whole year in context, see Yakumo's year-round climate.

Daytime high
20°
3rd warmest
Overnight low
17°
10th coldest
Rainfall
176 mm
13.1 wet days
Daylight
12 h 18 min
5:25 AM – 5:42 PM
Cloud cover
63%
4th clearest
Wind
13 km/h
9th windiest
Solar energy
3.73 kWh/m²
Travel score
5.7
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 22°C in the first days to 18°C by the end.

A typical September day in Yakumo reaches about 20°C in the afternoon and slips back to 17°C overnight — a 3°C spread between the day's warmth and the night's chill. On most days the high lands between 17°C and 22°C. Set against its neighbours, September runs about 2°C cooler than August and about 6°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
12219
22219
32218
42218
52118
62118
72118
82118
92118
102118
112117
122117
132017
142017
152017
162017
172016
182016
192016
201916
211916
221916
231915
241915
251815
261815
271815
281814
291814
301814

How September really feels in Yakumo

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.

Yakumo 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° / -5°6012.7179.30.0
Feb-1° / -4°569.912.410.30.0
Mar / -2°65118.811.60.0
Apr / 8510.52.313.10.5
May11° / 11611.6014.42.7
Jun16° / 13°11211.60154.8
Jul20° / 17°17214.8014.85.5
Aug22° / 19°20013.7013.76.0
Sep20° / 17°17613.1012.35.7
Oct14° / 10°11512.8010.83.7
Nov / 9712.94.79.60.6
Dec / -2°8413.614.790.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 28% 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 57%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13862
23961
33961
43862
53961
63961
74060
84060
94060
104159
114159
124258
134258
144357
154357
164456
174555
184654
194654
204753
214753
224753
234753
244753
254852
264753
274753
284753
294852
304753

Chance of precipitation in September

Any precipitation

Yakumo gets around 176 mm of rain over 13.1 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 44% 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
1443
1543
1642
1742
1842
1942
2042
2142
2242
2343
2443
2543
2643
2744
2844
2944
3044

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the comfortable band about 30% of days. Sticky, muggy-or-worse air turns up on roughly 15% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
161936319
262036308
372137288
482137267
592237257
6102337236
7112537216
8132637195
9142736185
10162835164
11182934154
12203033143
13223131133
14253130123
15273228112
1630332692
1732332492
1834332382
1937342171
2039341961
2142351751
2244351651
2346351441
2448351331
2550351230
2652351120
2753351020
285634910
295833810
306032710

Wind in September

Winds average 13 km/h in September.

Across September, daily wind ranges from about 12 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
112light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1713light breeze
1813light breeze
1913light breeze
2013light breeze
2113light breeze
2213light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours 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 84 minutes over September. Sunrise moves from 5:09 AM to 5:40 AM, and sunset from 6:09 PM to 5:16 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:096:09
213.05:106:07
312.95:116:05
412.95:126:03
512.85:136:02
612.85:146:00
712.75:155:58
812.75:165:56
912.65:175:54
1012.65:185:53
1112.55:195:51
1212.55:205:49
1312.45:225:47
1412.45:235:45
1512.35:245:44
1612.35:255:42
1712.25:265:40
1812.25:275:38
1912.15:285:36
2012.15:295:34
2112.05:305:32
2212.05:315:31
2311.95:325:29
2411.95:345:27
2511.85:355:25
2611.85:365:23
2711.75:375:22
2811.75:385:20
2911.65:395:18
3011.65:405:16

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.73 kWh/m².

For context, solar energy here swings from a low near 1.54 kWh/m² to a high of 5.4 kWh/m² in May across the year — September's 3.73 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.9Moderate
23.9Moderate
33.9Moderate
43.9Moderate
53.9Moderate
63.9Moderate
73.8Moderate
83.8Moderate
93.8Moderate
103.8Moderate
113.8Moderate
123.8Moderate
133.8Moderate
143.7Moderate
153.7Moderate
163.7Moderate
173.7Moderate
183.7Moderate
193.7Moderate
203.7Moderate
213.6Moderate
223.6Moderate
233.6Moderate
243.6Moderate
253.6Moderate
263.5Moderate
273.5Moderate
283.5Moderate
293.5Moderate
303.4Moderate
Planning a trip in September

Hazard calendar for Yakumo

In seasonPeak

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

Yakumo 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 Yakumo?

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

5.7
Sightseeing
2nd-best month of the year
2.9
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Yakumo for sightseeing.

What to pack for Yakumo in September

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

In September, Yakumo sees daytime highs around 20°C and nights near 17°C. Worth packing: rain gear. About 13 days see rain.

rain gear

Sea temperature near Yakumo in September

The nearest coast averages about 20°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 16 km away) is warmest in August at about 21°C and coldest in February near 4°C.

It's comfortable for a long swim from Aug 5 to Sep 17 — about 1.4 months when the water holds above 20°C.

0°10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarm
Sea temperature (°C)Comfort
Jan7Bracing
Feb4Bracing
Mar4Bracing
Apr6Bracing
May9Bracing
Jun14Bracing
Jul18Cool
Aug21Refreshing
Sep20Refreshing
Oct17Cool
Nov12Bracing
Dec9Bracing

UV index in Yakumo in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Yakumo peaks around August 18 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighVery highHighModerateLowAug 18UV 8Dec 22UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar3Moderate
Apr5High
May8Very high
Jun7High
Jul5Moderate
Aug9Very high
Sep6High
Oct4Moderate
Nov2Low
Dec1Low

Air quality in Yakumo 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 Yakumo is worst in April — around 17 µg/m³ PM2.5 (moderate), about 2.5× the cleanest month (December, 7 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1417 µg/m³Dec 177 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb11Good
Mar16Moderate
Apr17Moderate
May15Moderate
Jun9Good
Jul8Good
Aug8Good
Sep7Good
Oct9Good
Nov8Good
Dec7Good
Location & terrain

Where is Yakumo?

Yakumo sits at 42.3°N, 140.3°E, 9 m above sea level, in Japan. The nearest listed city is Honchō, 53 km away.

Topography around Yakumo

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

Within 3 km, the terrain around Yakumo has only modest variations in elevation — a maximum elevation change of 85 m around an average of 17 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 963 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,867 m.

The land around Yakumo is covered by cropland (49%) and water (22%) within 3 km, trees (59%) and water (30%) within 16 km, and water (54%) and trees (41%) within 80 km.

3 km
85 m
16 km
963 m
80 km
1,867 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Honchō 53 km · Date 55 km · Hokuto 57 km · Kamiiso 57 km · Muroran 60 km · Hakodate 66 km · Niseko 71 km · Noboribetsu 78 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 Yakumo (42.2539°, 140.2692°, elevation 9 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).