Semboku weather in September

In September, Semboku sees average daytime highs of 21°C and overnight lows near 14°C, with 187 mm of rain across 15.8 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 24°C in the first days to 19°C by the end. The sky is clear or mostly clear about 15% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Semboku's 5th-clearest and 9th-windiest month. For the whole year in context, see Semboku's year-round climate.

Daytime high
21°
3rd warmest
Overnight low
14°
10th coldest
Rainfall
187 mm
15.8 wet days
Daylight
12 h 18 min
5:24 AM – 5:39 PM
Cloud cover
72%
5th clearest
Wind
7 km/h
9th windiest
Solar energy
3.59 kWh/m²
Travel score
5.4
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 24°C in the first days to 19°C by the end.

A typical September day in Semboku reaches about 21°C in the afternoon and slips back to 14°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 18°C and 25°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°151015202530
Avg high (°C)Avg low (°C)
12417
22417
32417
42417
52317
62317
72316
82316
92316
102316
112215
122215
132215
142215
152214
162114
172114
182114
192113
202113
212013
222013
232012
242012
252012
261912
271911
281911
291911
301911

How September really feels in Semboku

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.

Semboku 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-1° / -8°10718.322.19.50.0
Feb / -7°9816.118.310.40.0
Mar / -4°13418.316.211.70.1
Apr10° / 13315.95132.1
May17° / 150150.114.24.6
Jun21° / 13°15815.1014.85.3
Jul24° / 18°25019.6014.55.2
Aug25° / 19°21617.9013.65.4
Sep21° / 14°18715.8012.35.4
Oct15° / 159150.310.94.1
Nov / 13717.66.49.81.2
Dec / -5°13019.419.29.20.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 15% 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 69%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
12674
22773
32773
42773
52872
62872
72872
82971
92971
102971
113070
123169
133169
143169
153268
163268
173268
183268
193268
203268
213268
223268
233268
243268
253268
263268
273268
283268
293268
303367

Chance of precipitation in September

Any precipitation

Semboku gets around 187 mm of rain over 15.8 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 54% and peaks near 58% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
158
258
357
457
557
657
757
857
957
1057
1157
1257
1357
1457
1556
1655
1755
1854
1953
2052
2152
2251
2350
2450
2550
2650
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 32% of days. Sticky, muggy-or-worse air turns up on roughly 16% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
161935327
262036317
372136306
472237296
582337275
692437265
7102536254
8122536234
9132636223
10152735213
11172834192
12192833182
13212931172
14242930151
15273028141
16303026131
17333025111
18363023100
1939312190
2042311980
2145311770
2248301660
2351301450
2453301340
2556291230
2658291030
276128920
286327820
296527710
306626710

Wind in September

Winds average 7 km/h in September.

Across September, daily wind ranges from about 6 km/h on the calmest days to 7 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min 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 78 minutes over September. Sunrise moves from 5:09 AM to 5:37 AM, and sunset from 6:04 PM to 5:15 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:096:04
212.95:106:03
312.85:116:01
412.85:125:59
512.75:135:58
612.75:145:56
712.75:155:54
812.65:165:53
912.65:175:51
1012.55:185:49
1112.55:195:48
1212.45:205:46
1312.45:215:44
1412.35:225:42
1512.35:235:41
1612.35:245:39
1712.25:255:37
1812.25:265:36
1912.15:275:34
2012.15:285:32
2112.05:285:30
2212.05:295:29
2311.95:305:27
2411.95:315:25
2511.95:325:24
2611.85:335:22
2711.85:345:20
2811.75:355:19
2911.75:365:17
3011.65:375:15

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.59 kWh/m².

For context, solar energy here swings from a low near 1.73 kWh/m² to a high of 5.22 kWh/m² in May across the year — September's 3.59 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.9Moderate
23.9Moderate
33.8Moderate
43.8Moderate
53.8Moderate
63.8Moderate
73.7Moderate
83.7Moderate
93.7Moderate
103.7Moderate
113.6Moderate
123.6Moderate
133.6Moderate
143.6Moderate
153.6Moderate
163.5Moderate
173.5Moderate
183.5Moderate
193.5Moderate
203.5Moderate
213.5Moderate
223.4Moderate
233.4Moderate
243.4Moderate
253.4Moderate
263.4Moderate
273.3Moderate
283.3Moderate
293.3Moderate
303.3Moderate
Planning a trip in September

Is September a good time to visit Semboku?

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

5.4
Sightseeing
1st-best month of the year
3.4
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Semboku for sightseeing.

What to pack for Semboku in September

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

In September, Semboku sees daytime highs around 21°C and nights near 14°C. Pack rain gear. About 16 days see rain.

rain gear

UV index in Semboku in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Semboku peaks around August 18 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 2 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighVery highHighModerateLowAug 18UV 9Jan 1UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun8Very high
Jul6High
Aug9Very high
Sep7High
Oct5Moderate
Nov2Moderate
Dec2Low

Air quality in Semboku 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 Semboku is worst in April — around 20 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (December, 9 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1420 µg/m³Dec 1610 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar19Moderate
Apr20Moderate
May19Moderate
Jun14Moderate
Jul12Moderate
Aug11Good
Sep11Good
Oct12Good
Nov11Good
Dec9Good
Location & terrain

Where is Semboku?

Semboku sits at 39.7°N, 140.7°E, 389 m above sea level, in Japan. The nearest listed city is Shizukuishi, 20 km away.

Topography around Semboku

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

Within 3 km, the terrain around Semboku has large variations in elevation — a maximum elevation change of 836 m around an average of 444 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,556 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,976 m.

The land around Semboku is covered by trees (88%) within 3 km, trees (91%) within 16 km, and trees (80%) within 80 km.

3 km
836 m
16 km
1,556 m
80 km
1,976 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Shizukuishi 20 km · Morioka 35 km · Takizawa 35 km · Yahaba 36 km · Ōmagari 37 km · Rokugō 37 km · Daisen 37 km · Hachimantai 39 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 Semboku (39.7093°, 140.7465°, elevation 389 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. 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).