Isumi weather in July

In July, Isumi sees average daytime highs of 26°C and overnight lows near 24°C, with 133 mm of rain across 11.8 wet days and about 14.1 hours of daylight. It is the 2nd-warmest and 7th-wettest month of the year here.

Highs climb over the month, from about 25°C in the first days to 27°C by the end. The sky is clear or mostly clear about 21% of the time in July, and the air most often feels oppressive.

Daylight stretches from about 14 h 18 min at the start of July to 13 h 48 min by month's end. Set against the rest of the year, July is Isumi's 11th-clearest and 10th-windiest month. For the whole year in context, see Isumi's year-round climate.

Daytime high
26°
2nd warmest
Overnight low
24°
11th coldest
Rainfall
133 mm
11.8 wet days
Daylight
14 h 12 min
4:39 AM – 6:49 PM
Cloud cover
71%
11th clearest
Wind
18 km/h
10th windiest
Solar energy
5.39 kWh/m²
Travel score
6.2
out of 10

Isumi is city in Chiba Prefecture, Japan.

Density
226/km²
people per km²
Founded
2005

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in July

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 25°C in the first days to 27°C by the end.

A typical July day in Isumi reaches about 26°C in the afternoon and slips back to 24°C overnight — a 3°C spread between the day's warmth and the night's chill. On most days the high lands between 23°C and 28°C. Set against its neighbours, July runs about 3°C warmer than June and about 2°C cooler than August.

15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
12522
22522
32522
42522
52523
62523
72523
82523
92623
102623
112623
122623
132623
142624
152624
162624
172624
182624
192624
202724
212724
222724
232724
242724
252724
262725
272725
282725
292725
302725
312725

Isumi weather by month

How July compares with the rest of the year at a glance. July is the 2nd-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan10° / 10810.79.92.5
Feb11° / 10110.610.72.4
Mar13° / 15914.611.73.2
Apr16° / 13°12612.612.94.8
May20° / 17°13811.813.85.9
Jun23° / 20°19013.514.35.8
Jul26° / 24°13311.814.16.2
Aug28° / 25°1001113.36.2
Sep25° / 23°18814.712.25.9
Oct21° / 19°23914.911.15.8
Nov17° / 14°14713.410.15.2
Dec13° / 10611.79.73.6

Cloud cover in July

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 21% of the time in July.

Beyond those clear spells, partly cloudy skies cover about 10% of July, with mostly cloudy or overcast conditions the remaining 69%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
12278
22278
32377
42575
52575
62674
72674
82773
92773
102872
112872
122872
132872
142872
153070
163070
173070
183070
193169
203169
213268
223367
233466
243565
253565
263763
273961
283961
294060
304159
314258

Chance of precipitation in July

Any precipitation

Isumi gets around 133 mm of rain over 11.8 wet days in July. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 37% and peaks near 48% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202531
Rain chance (%)
148
247
347
446
545
644
743
842
941
1040
1139
1238
1337
1436
1535
1634
1734
1833
1933
2033
2133
2233
2333
2433
2532
2632
2732
2831
2931
3031
3130

Humidity in July

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, July lands in the oppressive band about 54% of days. Sticky, muggy-or-worse air turns up on roughly 95% of them.

0%25%50%75%100%151015202531
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
111041471
21939492
31837522
41835533
51733554
61731565
71629595
81628596
91526617
100525628
1105246110
1205236111
1305226112
1405216014
1504206115
1604196017
1704185919
1804175821
1904175623
2003165625
2103155527
2203155230
2303145132
2403135034
2503124936
2603124739
2702114641
2802104543
290294345
300294247
310284149

Wind in July

Winds average 18 km/h in July.

Across July, daily wind ranges from about 16 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
118light breeze
218light breeze
318light breeze
418light breeze
518light breeze
618light breeze
718light breeze
818light breeze
918light breeze
1018light breeze
1118light breeze
1218light breeze
1318light breeze
1418light breeze
1518light breeze
1618light breeze
1718light breeze
1817light breeze
1917light breeze
2017light breeze
2117light breeze
2217light breeze
2317light breeze
2417light breeze
2517light breeze
2617light breeze
2717light breeze
2817light breeze
2917light breeze
3016light breeze
3116light breeze

Sunrise & sunset in July

DaylightNight

Daylight runs from about 14 h 18 min at the start of July to 13 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 30 minutes over July. Sunrise moves from 4:31 AM to 4:50 AM, and sunset from 6:52 PM to 6:39 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.34:316:52
214.34:326:52
314.34:326:52
414.34:336:52
514.34:336:52
614.34:346:52
714.34:346:52
814.34:356:51
914.34:356:51
1014.34:366:51
1114.24:366:51
1214.24:376:50
1314.24:376:50
1414.24:386:50
1514.24:396:49
1614.24:396:49
1714.14:406:48
1814.14:416:48
1914.14:416:47
2014.14:426:47
2114.14:436:46
2214.04:436:46
2314.04:446:45
2414.04:456:44
2514.04:456:44
2613.94:466:43
2713.94:476:42
2813.94:486:41
2913.94:486:41
3013.84:496:40
3113.84:506:39

Solar energy in July

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in July, about 5.39 kWh/m².

For context, solar energy here swings from a low near 2.25 kWh/m² to a high of 5.53 kWh/m² in August across the year — July's 5.39 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.0Bright
25.0Bright
35.0Bright
45.1Bright
55.1Bright
65.1Bright
75.2Bright
85.2Bright
95.2Bright
105.3Bright
115.3Bright
125.3Bright
135.3Bright
145.3Bright
155.4Bright
165.4Bright
175.4Bright
185.4Bright
195.5Bright
205.5Bright
215.5Bright
225.5Bright
235.6Bright
245.6Bright
255.6Bright
265.7Bright
275.7Bright
285.7Bright
295.7Bright
305.7Bright
315.8Bright
Planning a trip in July

Hazard calendar for Isumi

In seasonPeak

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

Isumi 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 July a good time to visit Isumi?

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

6.2
Sightseeing
1st-best month of the year
6.0
Beach & pool
2nd-best month of the year

July is a reasonable time to visit Isumi for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Isumi in July

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

In July, Isumi sees daytime highs around 26°C and nights near 24°C. Worth packing: light clothes, rain gear and sun protection. About 12 days see rain.

light clothesrain gearsun protection

Sea temperature near Isumi in July

The nearest coast averages about 24°C in July — 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 Isumi in July

LowModerateHighVery highExtreme

Clear-sky midday UV in July peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Isumi 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 Isumi in July

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where July falls, not just the annual average.

Air quality in Isumi 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 Isumi?

Isumi sits at 35.2°N, 140.4°E, 1 m above sea level, in Japan. The nearest listed city is Ōhara, 2.0 km away.

Topography around Isumi

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

Within 3 km, the terrain around Isumi has only modest variations in elevation — a maximum elevation change of 86 m around an average of 12 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 229 m; within 80 km, significant variations in elevation — a maximum elevation change of 396 m.

The land around Isumi is covered by water (59%) and trees (27%) within 3 km, water (62%) and trees (27%) within 16 km, and water (55%) and trees (21%) within 80 km.

3 km
86 m
16 km
229 m
80 km
396 m
treesgrasslandcroplandartificial surfaceswater
July weather nearby: Ōhara 2.0 km · Katsuura 12 km · Mobara 24 km · Kamogawa 31 km · Ōamishirasato 32 km · Ōami 33 km · Tōgane 36 km · Sodegaura 40 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 Isumi (35.23°, 140.4049°, elevation 1 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).