Yoichi weather in September

In September, Yoichi sees average daytime highs of 20°C and overnight lows near 15°C, with 139 mm of rain across 13.8 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 26% of the time in September, and the air most often feels dry.

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 Yoichi's 4th-clearest and 8th-windiest month. For the whole year in context, see Yoichi's year-round climate.

Daytime high
20°
3rd warmest
Overnight low
15°
10th coldest
Rainfall
139 mm
13.8 wet days
Daylight
12 h 18 min
5:23 AM – 5:40 PM
Cloud cover
62%
4th clearest
Wind
12 km/h
8th windiest
Solar energy
3.93 kWh/m²
Travel score
5.7
out of 10

Yoichi is town in Yoichi district, Hokkaidō, Japan.

Density
135/km²
people per km²
Founded
1900

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 22°C in the first days to 18°C by the end.

A typical September day in Yoichi reaches about 20°C in the afternoon and slips back to 15°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 17°C and 23°C. Set against its neighbours, September runs about 3°C cooler than August and about 6°C warmer than October.

10°15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12218
22218
32217
42217
52217
62217
72217
82217
92117
102116
112116
122116
132116
142116
152015
162015
172015
182015
192015
201914
211914
221914
231914
241914
251813
261813
271813
281813
291813
301712

How September really feels in Yoichi

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.

Yoichi 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-2° / -6°10321.524.59.20.0
Feb-1° / -5°8318.520.310.20.0
Mar / -3°7415.115.211.60.0
Apr / 6411.24.313.21.0
May13° / 7911.40.314.43.6
Jun18° / 12°679.6015.15.6
Jul22° / 17°11311.6014.96.2
Aug23° / 19°14513.2013.86.2
Sep20° / 15°13913.8012.35.7
Oct14° / 11314.80.510.83.7
Nov / 12718.410.99.50.7
Dec / -4°12722.322.68.90.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 26% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 56%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14159
24159
34159
44159
54159
64258
74258
84258
94159
104258
114258
124357
134456
144456
154555
164555
174555
184555
194654
204654
214654
224753
234753
244753
254555
264555
274555
284555
294654
304654

Chance of precipitation in September

Any precipitation

Yoichi gets around 139 mm of rain over 13.8 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 46% and peaks near 49% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
143
243
344
444
544
645
745
845
945
1046
1146
1246
1346
1446
1546
1646
1746
1846
1946
2046
2147
2247
2348
2448
2549
2649
2749
2849
2949
3049

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 38% of days. Sticky, muggy-or-worse air turns up on roughly 10% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
182837244
292937223
3102936213
4113036203
5133135183
6143234173
7163233163
8183332152
9203430132
10223429122
11253428112
12283526102
1330352492
1433352381
1536352171
1639341961
1742341761
1845341551
1948341351
2050331241
2153331040
225632930
235732830
246131620
256330520
266629410
276728410
286927310
297126300
307424200

Wind in September

Winds average 12 km/h in September.

Across September, daily wind ranges from about 11 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
111calm
211calm
311calm
411calm
511calm
611calm
711calm
811calm
911calm
1012calm
1112calm
1212calm
1312calm
1412calm
1512light breeze
1612light breeze
1712light breeze
1812light breeze
1913light breeze
2013light breeze
2113light breeze
2213light breeze
2313light breeze
2413light breeze
2513light 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 5:06 AM to 5:39 AM, and sunset from 6:08 PM to 5:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:066:08
213.05:076:06
312.95:086:04
412.95:096:02
512.85:106:00
612.85:115:59
712.75:125:57
812.75:135:55
912.65:155:53
1012.65:165:51
1112.55:175:49
1212.55:185:47
1312.45:195:46
1412.45:205:44
1512.35:215:42
1612.35:235:40
1712.25:245:38
1812.25:255:36
1912.15:265:34
2012.15:275:32
2112.05:285:31
2212.05:295:29
2311.95:315:27
2411.95:325:25
2511.85:335:23
2611.85:345:21
2711.75:355:19
2811.75:365:17
2911.65:385:16
3011.65:395:14

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.93 kWh/m².

For context, solar energy here swings from a low near 1.37 kWh/m² to a high of 5.69 kWh/m² in June across the year — September's 3.93 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.4Bright
24.3Bright
34.3Bright
44.3Bright
54.2Bright
64.2Bright
74.2Bright
84.1Bright
94.1Bright
104.1Bright
114.0Bright
124.0Bright
134.0Moderate
144.0Moderate
153.9Moderate
163.9Moderate
173.9Moderate
183.9Moderate
193.8Moderate
203.8Moderate
213.8Moderate
223.7Moderate
233.7Moderate
243.7Moderate
253.6Moderate
263.6Moderate
273.6Moderate
283.5Moderate
293.5Moderate
303.5Moderate
Planning a trip in September

Hazard calendar for Yoichi

In seasonPeak

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

Yoichi 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 Yoichi?

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

5.7
Sightseeing
3rd-best month of the year
3.0
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Yoichi for sightseeing.

What to pack for Yoichi in September

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

In September, Yoichi sees daytime highs around 20°C and nights near 15°C. Pack rain gear. About 14 days see rain.

rain gear

Sea temperature near Yoichi in September

The nearest coast averages about 21°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 21 km away) is warmest in August at about 21°C and coldest in February near 6°C.

It's comfortable for a long swim from Aug 1 to Sep 23 — about 1.8 months when the water holds above 20°C.

10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan7Bracing
Feb6Bracing
Mar6Bracing
Apr7Bracing
May10Bracing
Jun14Bracing
Jul19Cool
Aug21Refreshing
Sep21Refreshing
Oct17Cool
Nov13Bracing
Dec9Bracing

UV index in Yoichi 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 Yoichi peaks around August 18 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighHighVery highHighModerateLowAug 18UV 8Dec 21UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar3Moderate
Apr5High
May7Very high
Jun7High
Jul5Moderate
Aug9Very high
Sep6High
Oct4Moderate
Nov2Low
Dec1Low

Air quality in Yoichi 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 Yoichi is worst in April — around 21 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (December, 9 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1121 µg/m³Dec 169 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb15Moderate
Mar21Moderate
Apr21Moderate
May19Moderate
Jun13Moderate
Jul12Moderate
Aug11Good
Sep10Good
Oct12Good
Nov11Good
Dec9Good
Location & terrain

Where is Yoichi?

Yoichi sits at 43.2°N, 140.8°E, 2 m above sea level, in Japan. The nearest listed city is Otaru, 19 km away.

Topography around Yoichi

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

Within 3 km, the terrain around Yoichi has significant variations in elevation — a maximum elevation change of 280 m around an average of 47 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 873 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,867 m.

The land around Yoichi is covered by trees (46%) and water (31%) within 3 km, trees (56%) and water (37%) within 16 km, and trees (44%) and water (44%) within 80 km.

3 km
280 m
16 km
873 m
80 km
1,867 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Otaru 19 km · Kutchan 34 km · Niseko 44 km · Ishikari 47 km · Sapporo 49 km · Tōbetsu 61 km · Ebetsu 64 km · Kitahiroshima 70 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 Yoichi (43.2039°, 140.7703°, elevation 2 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).