Katsuura weather in September

In September, Katsuura sees average daytime highs of 26°C and overnight lows near 22°C, with 185 mm of rain across 14.9 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 24°C by the end. The sky is clear or mostly clear about 23% 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 Katsuura's 9th-clearest and 9th-windiest month. For the whole year in context, see Katsuura's year-round climate.

Daytime high
26°
3rd warmest
Overnight low
22°
10th coldest
Rainfall
185 mm
14.9 wet days
Daylight
12 h 12 min
5:27 AM – 5:40 PM
Cloud cover
66%
9th clearest
Wind
14 km/h
9th windiest
Solar energy
4.12 kWh/m²
Travel score
5.7
out of 10

Katsuura is city in Chiba Prefecture, Japan.

Density
180/km²
people per km²
Founded
1958

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 24°C by the end.

A typical September day in Katsuura reaches about 26°C in the afternoon and slips back to 22°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 23°C and 29°C. Set against its neighbours, September runs about 3°C cooler than August and about 5°C warmer than October.

15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12824
22824
32824
42824
52824
62824
72723
82723
92723
102723
112723
122723
132723
142623
152622
162622
172622
182622
192622
202521
212521
222521
232521
242521
252421
262420
272420
282420
292420
302420

How September really feels in Katsuura

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.

Katsuura 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
Jan10° / 918.60.69.92.3
Feb10° / 879.40.810.72.3
Mar13° / 14413.60.311.73.2
Apr17° / 12°11711.9012.95.0
May21° / 16°13111.8013.86.0
Jun24° / 20°17913.9014.35.8
Jul28° / 24°13913014.15.6
Aug29° / 25°11212.6013.35.2
Sep26° / 22°18514.9012.25.7
Oct21° / 17°22313.6011.16.0
Nov17° / 13°12711.4010.25.2
Dec12° / 859.809.73.5

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 61%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14456
24357
34357
44357
54258
64258
74258
84258
94258
104159
114060
124060
134060
144060
154060
164060
173961
183862
193763
203664
213664
223565
233565
243565
253565
263565
273565
283565
293565
303565

Chance of precipitation in September

Any precipitation

Katsuura gets around 185 mm of rain over 14.9 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 50% and peaks near 51% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
148
248
349
449
549
649
750
850
951
1051
1151
1251
1351
1451
1551
1651
1751
1851
1951
2050
2150
2250
2349
2449
2549
2648
2748
2848
2948
3048

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 35% of days. Sticky, muggy-or-worse air turns up on roughly 75% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1005185324
2005195323
3005205322
4006215122
5016225021
6017235020
7017244919
8018254818
9029254717
10029264616
110310274515
120311284413
130412294212
140513304111
151614313910
16171532379
17171632358
18181733337
191101934316
202112034295
212122135274
222132235243
233132336223
243142436202
253152536182
264162736162
274162836141
285172936131
296173036111
306183035101

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 14 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
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1514light breeze
1614light 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 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 5:15 AM to 5:37 AM, and sunset from 6:02 PM to 5:19 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:156:02
212.75:166:00
312.75:175:59
412.75:175:57
512.65:185:56
612.65:195:54
712.65:205:53
812.55:205:52
912.55:215:50
1012.45:225:49
1112.45:235:47
1212.45:245:46
1312.35:245:44
1412.35:255:43
1512.35:265:41
1612.25:275:40
1712.25:275:38
1812.15:285:37
1912.15:295:35
2012.15:305:34
2112.05:305:32
2212.05:315:31
2312.05:325:29
2411.95:335:28
2511.95:335:26
2611.85:345:25
2711.85:355:23
2811.85:365:22
2911.75:375:20
3011.75:375:19

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.12 kWh/m².

For context, solar energy here swings from a low near 2.27 kWh/m² to a high of 5.45 kWh/m² in August across the year — September's 4.12 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.8Bright
24.8Bright
34.8Bright
44.7Bright
54.7Bright
64.6Bright
74.6Bright
84.5Bright
94.5Bright
104.4Bright
114.3Bright
124.3Bright
134.3Bright
144.2Bright
154.1Bright
164.1Bright
174.0Bright
184.0Moderate
193.9Moderate
203.9Moderate
213.8Moderate
223.8Moderate
233.7Moderate
243.7Moderate
253.6Moderate
263.6Moderate
273.6Moderate
283.5Moderate
293.5Moderate
303.5Moderate
Planning a trip in September

Hazard calendar for Katsuura

In seasonPeak

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

Katsuura 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 Katsuura?

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

5.7
Sightseeing
4th-best month of the year
5.5
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Katsuura for sightseeing.

What to pack for Katsuura in September

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

In September, Katsuura sees daytime highs around 26°C and nights near 22°C. Pack rain gear. Worth having: light clothes. About 15 days see rain.

rain gearlight clothes

Sea temperature near Katsuura in September

The nearest coast averages about 26°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 26°C and coldest in February near 16°C.

It's comfortable for a long swim from May 22 to Dec 9 — about 6.6 months when the water holds above 20°C.

15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan18Cool
Feb16Cool
Mar16Cool
Apr18Cool
May20Cool
Jun22Refreshing
Jul24Refreshing
Aug26Warm
Sep26Warm
Oct24Refreshing
Nov22Refreshing
Dec20Cool

UV index in Katsuura 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 Katsuura peaks around August 11 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 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 highExtremeVery highHighModerateAug 11UV 10Dec 23UV 2
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5Moderate
Apr7High
May9Very high
Jun9Very high
Jul10Extreme
Aug10Extreme
Sep8Very high
Oct6High
Nov4Moderate
Dec2Moderate

Air quality in Katsuura 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 Katsuura is worst in April — around 22 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (September, 11 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateApr 1322 µg/m³Sep 911 µg/m³
PM2.5 (µg/m³)Level
Jan14Moderate
Feb17Moderate
Mar21Moderate
Apr22Moderate
May21Moderate
Jun16Moderate
Jul12Good
Aug11Good
Sep11Good
Oct14Moderate
Nov14Moderate
Dec13Moderate
Location & terrain

Where is Katsuura?

Katsuura sits at 35.1°N, 140.3°E, 23 m above sea level, in Japan. The nearest listed city is Isumi, 12 km away.

Topography around Katsuura

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

Within 3 km, the terrain around Katsuura has only modest variations in elevation — a maximum elevation change of 162 m around an average of 30 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 379 m; within 80 km, significant variations in elevation — a maximum elevation change of 394 m.

The land around Katsuura is covered by water (56%) and trees (35%) within 3 km, water (59%) and trees (34%) within 16 km, and water (59%) and trees (21%) within 80 km.

3 km
162 m
16 km
379 m
80 km
394 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Isumi 12 km · Ōhara 13 km · Kamogawa 20 km · Mobara 31 km · Minamibōsō 38 km · Sodegaura 40 km · Ōamishirasato 41 km · Ōami 41 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 Katsuura (35.1462°, 140.3151°, elevation 23 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).