Sōma weather in September

In September, Sōma sees average daytime highs of 23°C and overnight lows near 21°C, with 194 mm of rain across 14.1 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 24°C in the first days to 21°C by the end. The sky is clear or mostly clear about 22% of the time in September, and the air most often feels muggy.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Sōma's 9th-clearest and 9th-windiest month. For the whole year in context, see Sōma's year-round climate.

Daytime high
23°
3rd warmest
Overnight low
21°
10th coldest
Rainfall
194 mm
14.1 wet days
Daylight
12 h 12 min
5:23 AM – 5:38 PM
Cloud cover
68%
9th clearest
Wind
13 km/h
9th windiest
Solar energy
3.6 kWh/m²
Travel score
6.0
out of 10

Sōma is city in Fukushima Prefecture, Japan.

Density
176/km²
people per km²
Founded
1954

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 24°C in the first days to 21°C by the end.

A typical September day in Sōma reaches about 23°C in the afternoon and slips back to 21°C overnight — a 3°C spread between the day's warmth and the night's chill. On most days the high lands between 20°C and 26°C. Set against its neighbours, September runs about 2°C cooler than August and about 4°C warmer than October.

15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12522
22522
32422
42422
52422
62422
72422
82422
92422
102422
112421
122421
132421
142321
152321
162321
172320
182320
192320
202320
212220
222220
232219
242219
252219
262219
272119
282119
292119
302118

How September really feels in Sōma

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.

Sōma weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 628.22.89.70.7
Feb / 527.42.910.50.7
Mar / 9810.21.511.71.6
Apr12° / 11310.50.212.93.3
May16° / 13°12111.20145.0
Jun20° / 17°13512.8014.65.5
Jul23° / 21°19116.2014.35.6
Aug25° / 23°14813.2013.56.2
Sep23° / 21°19414.1012.36.0
Oct19° / 16°19111.60115.8
Nov14° / 10°788.10104.3
Dec / 588.71.29.42.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 22% 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 62%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13961
23961
33961
43961
53961
64060
74060
84060
94060
104060
113862
123961
133862
143862
153763
163763
173565
183565
193565
203565
213565
223565
233565
243565
253763
263664
273664
283763
293763
303862

Chance of precipitation in September

Any precipitation

Sōma gets around 194 mm of rain over 14.1 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 47% and peaks near 48% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
147
248
348
448
548
648
748
848
948
1048
1148
1248
1348
1448
1548
1648
1748
1848
1947
2047
2146
2246
2346
2446
2545
2645
2745
2845
2944
3044

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 30% of days. Sticky, muggy-or-worse air turns up on roughly 53% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1031435426
2031536416
3031636405
4031637404
5041736394
6041837373
7051937363
8162037352
9162137332
10172237312
11282336301
12292436281
133102536261
143112635241
154122734221
165132833200
176143032180
187153131160
198173130140
2010183228120
2111193327100
221220332590
231421332480
241522342370
251623342150
261824342040
271925341840
282026341730
292227331520
302328331420

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
212light breeze
312light breeze
412light breeze
512light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2214light 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 12 h 54 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 72 minutes over September. Sunrise moves from 5:10 AM to 5:36 AM, and sunset from 6:02 PM to 5:15 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:106:02
212.85:116:00
312.85:125:59
412.75:135:57
512.75:145:55
612.75:155:54
712.65:165:52
812.65:165:51
912.55:175:49
1012.55:185:47
1112.45:195:46
1212.45:205:44
1312.45:215:43
1412.35:225:41
1512.35:235:39
1612.25:235:38
1712.25:245:36
1812.25:255:35
1912.15:265:33
2012.15:275:31
2112.05:285:30
2212.05:295:28
2311.95:305:26
2411.95:305:25
2511.95:315:23
2611.85:325:22
2711.85:335:20
2811.75:345:18
2911.75:355:17
3011.75:365:15

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.6 kWh/m².

For context, solar energy here swings from a low near 2.21 kWh/m² to a high of 5.4 kWh/m² in May across the year — September's 3.6 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
14.0Moderate
23.9Moderate
33.9Moderate
43.9Moderate
53.8Moderate
63.8Moderate
73.8Moderate
83.8Moderate
93.7Moderate
103.7Moderate
113.7Moderate
123.6Moderate
133.6Moderate
143.6Moderate
153.6Moderate
163.6Moderate
173.5Moderate
183.5Moderate
193.5Moderate
203.5Moderate
213.5Moderate
223.4Moderate
233.4Moderate
243.4Moderate
253.4Moderate
263.3Moderate
273.3Moderate
283.3Moderate
293.3Moderate
303.3Moderate
Planning a trip in September

Hazard calendar for Sōma

In seasonPeak

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

Sōma sits in the Pacific typhoon belt; the season peaks July–October.

Sōma's rainy season runs March–October, when most of the year's rain falls.

Pacific typhoon
Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Sōma?

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

6.0
Sightseeing
2nd-best month of the year
4.6
Beach & pool
2nd-best month of the year

September is a reasonable time to visit Sōma for sightseeing.

What to pack for Sōma in September

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

In September, Sōma sees daytime highs around 23°C and nights near 21°C. Pack rain gear. Worth having: light clothes. About 14 days see rain.

rain gearlight clothes

Sea temperature near Sōma in September

The nearest coast averages about 23°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 19 km away) is warmest in August at about 24°C and coldest in March near 9°C.

It's comfortable for a long swim from Jul 7 to Oct 10 — about 3.2 months when the water holds above 20°C.

5°10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan12Bracing
Feb9Bracing
Mar9Bracing
Apr11Bracing
May14Bracing
Jun18Cool
Jul21Refreshing
Aug24Refreshing
Sep23Refreshing
Oct19Cool
Nov17Cool
Dec14Bracing

UV index in Sōma in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 8 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Sōma peaks around July 20 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJul 20UV 9Jan 10UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun8Very high
Jul9Very high
Aug9Very high
Sep8Very high
Oct5High
Nov3Moderate
Dec2Low

Air quality in Sōma 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 Sōma is worst in April — around 20 µg/m³ PM2.5 (moderate), about 2.4× the cleanest month (December, 9 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1720 µg/m³Dec 169 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar19Moderate
Apr20Moderate
May19Moderate
Jun14Moderate
Jul12Good
Aug10Good
Sep10Good
Oct10Good
Nov10Good
Dec9Good
Location & terrain

Where is Sōma?

Sōma sits at 37.8°N, 140.9°E, 9 m above sea level, in Japan. The nearest listed city is Minami-Sōma, 19 km away.

Topography around Sōma

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

Within 3 km, the terrain around Sōma has only modest variations in elevation — a maximum elevation change of 79 m around an average of 14 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 689 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,031 m.

The land around Sōma is covered by cropland (41%), artificial surfaces (27%) and trees (25%) within 3 km, trees (45%) and water (35%) within 16 km, and trees (54%) and water (32%) within 80 km.

3 km
79 m
16 km
689 m
80 km
2,031 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Minami-Sōma 19 km · Kakuda 24 km · Watari 28 km · Yanagawamachi-saiwaichō 30 km · Ōkawara 33 km · Hobaramachi 33 km · Namie 35 km · Iwanuma 35 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 Sōma (37.7928°, 140.9294°, 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).