Iwaki weather in September

In September, Iwaki sees average daytime highs of 23°C and overnight lows near 20°C, with 192 mm of rain across 14.1 wet days and about 12.3 hours of daylight. It is the 2nd-warmest and 2nd-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 23% of the time in September, and the air most often feels muggy.

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 Iwaki's 10th-clearest and 9th-windiest month. For the whole year in context, see Iwaki's year-round climate.

Daytime high
23°
2nd warmest
Overnight low
20°
10th coldest
Rainfall
192 mm
14.1 wet days
Daylight
12 h 12 min
5:24 AM – 5:38 PM
Cloud cover
67%
10th clearest
Wind
14 km/h
9th windiest
Solar energy
3.88 kWh/m²
Travel score
5.9
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 21°C by the end.

A typical September day in Iwaki reaches about 23°C in the afternoon and slips back to 20°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 25°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)
12422
22422
32422
42422
52421
62421
72421
82421
92421
102421
112421
122321
132321
142320
152320
162320
172320
182320
192220
202220
212219
222219
232219
242219
252219
262119
272118
282118
292118
302118

How September really feels in Iwaki

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.

Iwaki weather by month

How September compares with the rest of the year at a glance. September is the 2nd-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 7181.59.71.1
Feb / 6881.910.61.1
Mar10° / 12512.1111.72.1
Apr13° / 13411.90.212.93.6
May17° / 13°145120145.1
Jun20° / 17°14713.7014.55.4
Jul23° / 20°17514.5014.35.9
Aug25° / 22°12611.8013.46.5
Sep23° / 20°19214.1012.35.9
Oct19° / 15°22313.40115.6
Nov14° / 10°1119.80104.4
Dec10° / 738.60.29.52.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 23% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 62%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13862
23862
33862
43862
53862
63862
73961
83961
93961
103862
113961
123961
134060
143961
153961
163862
173862
183862
193763
203763
213763
223763
233763
243763
253862
263961
273961
283961
293961
303961

Chance of precipitation in September

Any precipitation

Iwaki gets around 192 mm of rain over 14.1 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 48% and peaks near 48% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
147
247
348
448
548
648
748
848
948
1048
1148
1248
1348
1448
1548
1648
1748
1848
1948
2048
2148
2248
2348
2448
2548
2648
2748
2848
2948
3048

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 31% of days. Sticky, muggy-or-worse air turns up on roughly 56% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1021335483
2021435472
3031435462
4031535452
5031635442
6041735422
7051835411
8051836401
9061936381
10172036361
11182036341
12192136321
132102236301
143112336271
154122435250
164132535230
175142634210
186152733180
198162832160
209172931140
2110183029130
2211193128110
231319322790
241420332580
251521342370
261622352260
271722352050
281923361940
292023361730
302124371620

Wind in September

Winds average 14 km/h in September.

Across September, daily wind ranges from about 13 km/h on the calmest days to 15 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1014light breeze
1114light breeze
1214light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1915light breeze
2015light breeze
2115light breeze
2215light breeze
2315light breeze
2415light breeze
2515light breeze
2615light breeze
2715light breeze
2815light breeze
2915light breeze
3015light breeze

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 5:11 AM to 5:36 AM, and sunset from 6:01 PM to 5:16 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:116:01
212.85:126:00
312.85:135:58
412.75:145:57
512.75:155:55
612.65:155:54
712.65:165:52
812.65:175:50
912.55:185:49
1012.55:195:47
1112.45:205:46
1212.45:205:44
1312.45:215:43
1412.35:225:41
1512.35:235:39
1612.25:245:38
1712.25:255:36
1812.25:255:35
1912.15:265:33
2012.15:275:31
2112.05:285:30
2212.05:295:28
2311.95:305:27
2411.95:315:25
2511.95:315:24
2611.85:325:22
2711.85:335:20
2811.75:345:19
2911.75:355:17
3011.75:365:16

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.88 kWh/m².

For context, solar energy here swings from a low near 2.32 kWh/m² to a high of 5.47 kWh/m² in May across the year — September's 3.88 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
124.0Moderate
134.0Moderate
143.9Moderate
153.9Moderate
163.9Moderate
173.8Moderate
183.8Moderate
193.7Moderate
203.7Moderate
213.7Moderate
223.6Moderate
233.6Moderate
243.6Moderate
253.5Moderate
263.5Moderate
273.5Moderate
283.5Moderate
293.4Moderate
303.4Moderate
Planning a trip in September

Hazard calendar for Iwaki

In seasonPeak

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

Iwaki 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 Iwaki?

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

5.9
Sightseeing
2nd-best month of the year
4.5
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Iwaki for sightseeing.

What to pack for Iwaki in September

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

In September, Iwaki sees daytime highs around 23°C and nights near 20°C. Pack rain gear. Worth having: light clothes. About 14 days see rain.

rain gearlight clothes

Sea temperature near Iwaki 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 12°C.

It's comfortable for a long swim from Jul 1 to Oct 22 — about 3.7 months when the water holds above 20°C.

10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan14Bracing
Feb12Bracing
Mar12Bracing
Apr14Bracing
May16Cool
Jun19Cool
Jul21Refreshing
Aug24Refreshing
Sep23Refreshing
Oct20Refreshing
Nov18Cool
Dec16Cool

UV index in Iwaki 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 Iwaki peaks around July 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 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJul 18UV 9Jan 1UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug9Very high
Sep8Very high
Oct5High
Nov3Moderate
Dec2Low

Air quality in Iwaki 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 Iwaki is worst in April — around 19 µg/m³ PM2.5 (moderate), about 2.8× the cleanest month (December, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 2219 µg/m³Dec 177 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb11Good
Mar17Moderate
Apr19Moderate
May19Moderate
Jun14Moderate
Jul12Moderate
Aug11Good
Sep10Good
Oct10Good
Nov9Good
Dec7Good
Location & terrain

Where is Iwaki?

Iwaki sits at 37.0°N, 140.9°E, 9 m above sea level, in Japan. The nearest listed city is Kitaibaraki, 32 km away.

Topography around Iwaki

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

Within 3 km, the terrain around Iwaki has only modest variations in elevation — a maximum elevation change of 129 m around an average of 35 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 776 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,678 m.

The land around Iwaki is covered by artificial surfaces (46%) and trees (41%) within 3 km, trees (57%) and water (22%) within 16 km, and trees (55%) and water (32%) within 80 km.

3 km
129 m
16 km
776 m
80 km
1,678 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Kitaibaraki 32 km · Takahagi 40 km · Ishikawa 40 km · Tamura 49 km · Namie 49 km · Sukagawa 51 km · Funehikimachi-funehiki 52 km · Yabuki 53 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 Iwaki (37.05°, 140.8833°, 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).