Niimi weather in September

In September, Niimi sees average daytime highs of 26°C and overnight lows near 18°C, with 201 mm of rain across 13.1 wet days and about 12.2 hours of daylight. It is the 3rd-warmest and 2nd-wettest month of the year here.

Highs ease over the month, from about 28°C in the first days to 23°C by the end. The sky is clear or mostly clear about 23% of the time in September, and the air most often feels humid.

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 Niimi's 8th-clearest and 7th-windiest month. For the whole year in context, see Niimi's year-round climate.

Daytime high
26°
3rd warmest
Overnight low
18°
10th coldest
Rainfall
201 mm
13.1 wet days
Daylight
12 h 12 min
5:54 AM – 6:07 PM
Cloud cover
66%
8th clearest
Wind
8 km/h
7th windiest
Solar energy
4.08 kWh/m²
Travel score
6.1
out of 10

Niimi is city in Okayama Prefecture, Japan.

Density
39/km²
people per km²
Founded
2005

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 28°C in the first days to 23°C by the end.

A typical September day in Niimi reaches about 26°C in the afternoon and slips back to 18°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 29°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

10°15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12820
22820
32820
42820
52820
62719
72719
82719
92719
102719
112719
122618
132618
142618
152618
162618
172517
182517
192517
202517
212517
222416
232416
242416
252416
262415
272415
282315
292315
302315

How September really feels in Niimi

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.

Niimi 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°549.76.59.90.5
Feb / -1°619.76.210.70.9
Mar11° / 10812.43.111.72.7
Apr17° / 11710.80.312.95.3
May22° / 12°13811.1013.86.4
Jun25° / 17°19414.2014.35.8
Jul29° / 21°23616.9014.14.6
Aug30° / 22°14914.4013.34.5
Sep26° / 18°20113.1012.26.1
Oct20° / 11°1098.1011.16.6
Nov14° / 678.10.210.24.4
Dec / 598.83.69.71.6

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 17% of September, with mostly cloudy or overcast conditions the remaining 60%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13862
23862
33862
43862
53862
64060
74060
84060
93961
103961
113961
124060
134060
143961
153961
163961
173961
183862
193961
203961
213961
224060
234060
244060
254159
264159
274258
284357
294357
304357

Chance of precipitation in September

Any precipitation

Niimi gets around 201 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 43% and peaks near 47% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
146
246
347
447
547
647
747
847
946
1046
1146
1245
1345
1444
1543
1643
1742
1842
1942
2041
2141
2240
2339
2439
2538
2637
2737
2836
2936
3035

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the humid band about 27% of days. Sticky, muggy-or-worse air turns up on roughly 39% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
107254226
217264125
318274124
419284022
5110283921
6211293920
7212303819
8313303717
9314313616
10415313515
11516313414
12617313313
13719313212
14820313111
151021302910
16112230289
17132329278
18142429257
19162528246
20182628226
21192727215
22212827195
23232926184
24243025164
25263125153
26283224143
27293223132
28313322122
29333321112
30353420111

Wind in September

Winds average 8 km/h in September.

Across September, daily wind ranges from about 8 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
218calm
228calm
238calm
248calm
258calm
268calm
278calm
288calm
298calm
308calm

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 5:43 AM to 6:05 AM, and sunset from 6:29 PM to 5:46 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:436:29
212.75:436:28
312.75:446:26
412.75:456:25
512.65:466:23
612.65:466:22
712.65:476:20
812.55:486:19
912.55:496:17
1012.45:496:16
1112.45:506:14
1212.45:516:13
1312.35:526:11
1412.35:526:10
1512.35:536:08
1612.25:546:07
1712.25:556:05
1812.15:556:04
1912.15:566:02
2012.15:576:01
2112.05:585:59
2212.05:595:58
2312.05:595:56
2411.96:005:55
2511.96:015:53
2611.86:025:52
2711.86:025:51
2811.86:035:49
2911.76:045:48
3011.76:055:46

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.08 kWh/m².

For context, solar energy here swings from a low near 2.2 kWh/m² to a high of 5.57 kWh/m² in May across the year — September's 4.08 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.5Bright
24.5Bright
34.5Bright
44.4Bright
54.4Bright
64.4Bright
74.3Bright
84.3Bright
94.3Bright
104.2Bright
114.2Bright
124.2Bright
134.2Bright
144.1Bright
154.1Bright
164.1Bright
174.0Bright
184.0Bright
194.0Bright
204.0Moderate
214.0Moderate
223.9Moderate
233.9Moderate
243.9Moderate
253.9Moderate
263.8Moderate
273.8Moderate
283.8Moderate
293.8Moderate
303.8Moderate
Planning a trip in September

Hazard calendar for Niimi

In seasonPeak

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

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

Niimi'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 Niimi?

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

6.1
Sightseeing
3rd-best month of the year
5.7
Beach & pool
2nd-best month of the year

September is a reasonable time to visit Niimi for sightseeing.

What to pack for Niimi in September

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

In September, Niimi sees daytime highs around 26°C and nights near 18°C. Worth packing: light clothes and rain gear. About 13 days see rain.

light clothesrain gear

Sea temperature near Niimi in September

The nearest coast averages about 27°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 68 km away) is warmest in August at about 27°C and coldest in February near 13°C.

It's comfortable for a long swim from Jun 3 to Nov 12 — about 5.4 months when the water holds above 20°C.

10°15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan14Bracing
Feb13Bracing
Mar13Bracing
Apr15Cool
May18Cool
Jun22Refreshing
Jul25Warm
Aug27Warm
Sep27Warm
Oct23Refreshing
Nov20Cool
Dec16Cool

UV index in Niimi in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Niimi peaks around July 15 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highModerateJul 15UV 10Dec 23UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5High
Apr7Very high
May8Very high
Jun10Very high
Jul10Extreme
Aug9Very high
Sep9Very high
Oct6High
Nov4Moderate
Dec3Moderate

Air quality in Niimi 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 Niimi is worst in April — around 23 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (October, 11 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateApr 1322 µg/m³Oct 1511 µg/m³
PM2.5 (µg/m³)Level
Jan14Moderate
Feb17Moderate
Mar22Moderate
Apr23Moderate
May20Moderate
Jun18Moderate
Jul14Moderate
Aug13Moderate
Sep12Moderate
Oct11Good
Nov13Moderate
Dec12Moderate
Location & terrain

Where is Niimi?

Niimi sits at 35.0°N, 133.5°E, 193 m above sea level, in Japan. The nearest listed city is Takahashi, 26 km away.

Topography around Niimi

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

Within 3 km, the terrain around Niimi has significant variations in elevation — a maximum elevation change of 489 m around an average of 336 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 1,045 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,692 m.

The land around Niimi is covered by trees (83%) within 3 km, trees (94%) within 16 km, and trees (73%) within 80 km.

3 km
489 m
16 km
1,045 m
80 km
1,692 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Takahashi 26 km · Maniwa 27 km · Ibara 43 km · Sōja 43 km · Shōbara 44 km · Kannabechō-yahiro 47 km · Tsuyama 49 km · Fuchūchō 50 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 Niimi (34.9833°, 133.4667°, elevation 193 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).