Asahi weather in September

In September, Asahi sees average daytime highs of 25°C and overnight lows near 22°C, with 170 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 27°C in the first days to 23°C by the end. The sky is clear or mostly clear about 25% of the time in September, and the air most often feels oppressive.

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 Asahi's 9th-clearest and 8th-windiest month. For the whole year in context, see Asahi's year-round climate.

Daytime high
25°
3rd warmest
Overnight low
22°
10th coldest
Rainfall
170 mm
13.1 wet days
Daylight
12 h 12 min
5:25 AM – 5:38 PM
Cloud cover
65%
9th clearest
Wind
17 km/h
8th windiest
Solar energy
4.24 kWh/m²
Travel score
6.1
out of 10

Asahi is city in Chiba Prefecture, Japan.

Density
496/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 27°C in the first days to 23°C by the end.

A typical September day in Asahi reaches about 25°C in the afternoon and slips back to 22°C overnight — a 3°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 28°C. Set against its neighbours, September runs about 3°C cooler than August and about 4°C warmer than October.

15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12724
22724
32724
42724
52724
62724
72723
82623
92623
102623
112623
122623
132623
142623
152522
162522
172522
182522
192522
202522
212422
222421
232421
242421
252421
262421
272421
282320
292320
302320

Asahi 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 daysDaylight (hours)Travel score
Jan10° / 949.39.92.2
Feb10° / 879.610.62.2
Mar12° / 14213.711.73.1
Apr16° / 12°11912.612.94.8
May20° / 16°13411.913.95.9
Jun23° / 20°16512.914.45.9
Jul26° / 23°1331214.26.2
Aug28° / 24°889.913.46.3
Sep25° / 22°17013.112.26.1
Oct21° / 18°22613.911.15.9
Nov17° / 13°12211.810.15.1
Dec12° / 91109.63.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 25% 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 59%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14753
24555
34555
44654
54654
64555
74555
84555
94555
104456
114456
124456
134357
144357
154159
164060
174060
184060
193862
203862
213763
223763
233664
243664
253763
263664
273664
283763
293763
303763

Chance of precipitation in September

Any precipitation

Asahi gets around 170 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 44% and peaks near 46% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
139
240
340
441
541
642
742
843
944
1044
1145
1245
1345
1446
1546
1646
1746
1846
1946
2046
2146
2245
2345
2445
2545
2645
2746
2846
2946
3046

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the oppressive band about 34% of days. Sticky, muggy-or-worse air turns up on roughly 72% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1015215024
2015225023
3016234922
4016244921
5017244920
6017254818
7028264717
8029274616
90210274515
100311284513
110412284412
120413294311
131514294110
14161530409
15171630388
16281731367
17291831346
182101931325
193112132304
204122232283
214132332263
225132432242
236142532222
246152632201
257152633181
268162733161
279162833141
289162933120
2910172932110
3011173032100

Wind in September

Winds average 17 km/h in September.

Across September, daily wind ranges from about 16 km/h on the calmest days to 19 km/h at its breeziest. It stays fairly steady from day to day.

0510152025151015202530
Wind speed (km/h)Feels
116light breeze
216light breeze
316light breeze
416light breeze
516light breeze
616light breeze
716light breeze
816light breeze
917light breeze
1017light breeze
1117light breeze
1217light breeze
1317light breeze
1417light breeze
1517light breeze
1617light breeze
1718light breeze
1818light breeze
1918light breeze
2018light breeze
2118light breeze
2218light breeze
2318light breeze
2418light breeze
2518light breeze
2618light breeze
2718light breeze
2818light breeze
2919light breeze
3019light 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 5:13 AM to 5:36 AM, and sunset from 6:01 PM to 5:17 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:136:01
212.85:145:59
312.75:155:58
412.75:165:57
512.65:165:55
612.65:175:54
712.65:185:52
812.55:195:51
912.55:205:49
1012.55:205:48
1112.45:215:46
1212.45:225:44
1312.35:235:43
1412.35:235:41
1512.35:245:40
1612.25:255:38
1712.25:265:37
1812.15:275:35
1912.15:275:34
2012.15:285:32
2112.05:295:31
2212.05:305:29
2312.05:315:28
2411.95:315:26
2511.95:325:25
2611.85:335:23
2711.85:345:22
2811.85:355:20
2911.75:355:19
3011.75:365:17

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.24 kWh/m².

For context, solar energy here swings from a low near 2.28 kWh/m² to a high of 5.54 kWh/m² in May across the year — September's 4.24 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.9Bright
24.9Bright
34.8Bright
44.8Bright
54.8Bright
64.7Bright
74.7Bright
84.6Bright
94.6Bright
104.5Bright
114.5Bright
124.4Bright
134.4Bright
144.3Bright
154.3Bright
164.2Bright
174.2Bright
184.1Bright
194.0Bright
204.0Bright
214.0Moderate
223.9Moderate
233.9Moderate
243.8Moderate
253.8Moderate
263.7Moderate
273.7Moderate
283.6Moderate
293.6Moderate
303.5Moderate
Planning a trip in September

Hazard calendar for Asahi

In seasonPeak

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

Asahi 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 Asahi?

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
5.6
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Asahi for sightseeing.

What to pack for Asahi in September

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

In September, Asahi sees daytime highs around 25°C and nights near 22°C. Worth packing: light clothes and rain gear. About 13 days see rain.

light clothesrain gear

Sea temperature near Asahi in September

The nearest coast averages about 25°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 25°C and coldest in February near 15°C.

It's comfortable for a long swim from Jun 5 to Nov 22 — about 5.6 months when the water holds above 20°C.

15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan16Cool
Feb15Bracing
Mar15Cool
Apr16Cool
May19Cool
Jun21Refreshing
Jul23Refreshing
Aug25Warm
Sep25Warm
Oct23Refreshing
Nov21Refreshing
Dec18Cool

UV index in Asahi 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 Asahi peaks around August 12 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 2 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highVery highHighModerateAug 12UV 10Jan 1UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar4Moderate
Apr7High
May8Very high
Jun9Very high
Jul10Very high
Aug10Extreme
Sep8Very high
Oct6High
Nov4Moderate
Dec2Moderate

Air quality in Asahi 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 Asahi is worst in April — around 20 µg/m³ PM2.5 (moderate), about 2.7× the cleanest month (December, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1920 µg/m³Dec 178 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb11Good
Mar18Moderate
Apr20Moderate
May19Moderate
Jun14Moderate
Jul12Good
Aug11Good
Sep10Good
Oct10Good
Nov9Good
Dec7Good
Location & terrain

Where is Asahi?

Asahi sits at 35.7°N, 140.7°E, 5 m above sea level, in Japan. The nearest listed city is Sōsa, 9.0 km away.

Topography around Asahi

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

Within 3 km, the terrain around Asahi has only modest variations in elevation — a maximum elevation change of 19 m around an average of 7 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 71 m; within 80 km, large variations in elevation — a maximum elevation change of 840 m.

The land around Asahi is covered by cropland (41%) and artificial surfaces (39%) within 3 km, water (34%), cropland (27%) and trees (22%) within 16 km, and water (44%) and trees (24%) within 80 km.

3 km
19 m
16 km
71 m
80 km
840 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Sōsa 9.0 km · Yōkaichiba 9.0 km · Omigawa 15 km · Hasaki 17 km · Choshi 17 km · Yokoshiba 17 km · Kamisu 20 km · Sawara 23 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 Asahi (35.7167°, 140.65°, elevation 5 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).