Iwai weather in June

In June, Iwai sees average daytime highs of 23°C and overnight lows near 17°C, with 222 mm of rain across 19.5 wet days and about 14.4 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Highs climb over the month, from about 22°C in the first days to 25°C by the end. The sky is clear or mostly clear about 7% of the time in June, and the air most often feels humid.

Daylight stretches from about 14 h 12 min at the start of June to 14 h 24 min by month's end. Set against the rest of the year, June is Iwai's 12th-clearest and 9th-windiest month. For the whole year in context, see Iwai's year-round climate.

Daytime high
23°
4th warmest
Overnight low
17°
9th coldest
Rainfall
222 mm
19.5 wet days
Daylight
14 h 24 min
4:31 AM – 6:56 PM
Cloud cover
83%
12th clearest
Wind
6 km/h
9th windiest
Solar energy
4.35 kWh/m²
Travel score
4.9
out of 10

Temperature in June

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 22°C in the first days to 25°C by the end.

A typical June day in Iwai reaches about 23°C in the afternoon and slips back to 17°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 19°C and 27°C. Set against its neighbours, June runs about 3°C warmer than May and about 4°C cooler than July.

10°15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12215
22215
32215
42215
52215
62216
72216
82216
92316
102316
112316
122316
132317
142317
152317
162317
172317
182317
192418
202418
212418
222418
232418
242418
252419
262519
272519
282519
292519
302519

How June really feels in Iwai

Once humidity and wind are folded in, June 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

June sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Iwai weather by month

How June compares with the rest of the year at a glance. June is the 4th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -2°778.54.49.91.0
Feb / -1°759.64.610.61.2
Mar11° / 13915.24.711.72.5
Apr16° / 14614.60.912.94.5
May21° / 13°16615.6013.95.5
Jun23° / 17°22219.5014.44.9
Jul27° / 21°24321.8014.24.5
Aug28° / 22°20521013.44.4
Sep25° / 18°24918.3012.25.2
Oct19° / 13°24216.2011.15.2
Nov14° / 10111.30.210.14.1
Dec10° / 688.31.49.62.2

Cloud cover in June

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 7% of the time in June, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 10% of June, with mostly cloudy or overcast conditions the remaining 83%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
12773
22575
32575
42377
52377
62278
72080
82080
91882
101882
111882
121684
131585
141486
151486
161486
171387
181387
191387
201387
211387
221486
231585
241585
251585
261585
271585
281585
291783
301783

Chance of precipitation in June

Any precipitation

Iwai gets around 222 mm of rain over 19.5 wet days in June. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 66% and peaks near 73% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
152
253
354
455
556
657
758
859
960
1062
1163
1264
1366
1467
1568
1669
1770
1871
1971
2072
2172
2272
2372
2472
2573
2673
2773
2873
2973
3073

Humidity in June

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, June lands in the humid band about 37% of days. Sticky, muggy-or-worse air turns up on roughly 26% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
132452120
229452330
327452530
424452640
522452840
620443050
718433260
816423470
914413690
10123938110
11103839120
1293641140
1373442160
1463243181
1552944211
1652745231
1742545251
1832345272
1932145293
2031944304
2121743325
2221642346
2321441367
2421240388
25111393910
26110374111
2719364213
2818344314
2917324416
3017304517

Wind in June

Winds average 6 km/h in June.

Across June, daily wind ranges from about 6 km/h on the calmest days to 6 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

Sunrise & sunset in June

DaylightNight

Daylight runs from about 14 h 12 min at the start of June to 14 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 12 minutes over June. Sunrise moves from 4:33 AM to 4:34 AM, and sunset from 6:48 PM to 6:58 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
114.24:336:48
214.34:336:48
314.34:336:49
414.34:326:50
514.34:326:50
614.34:326:51
714.34:326:51
814.34:326:52
914.34:316:52
1014.44:316:53
1114.44:316:53
1214.44:316:54
1314.44:316:54
1414.44:316:55
1514.44:316:55
1614.44:316:56
1714.44:316:56
1814.44:316:56
1914.44:316:57
2014.44:316:57
2114.44:326:57
2214.44:326:57
2314.44:326:58
2414.44:326:58
2514.44:336:58
2614.44:336:58
2714.44:336:58
2814.44:336:58
2914.44:346:58
3014.44:346:58

Solar energy in June

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in June, about 4.35 kWh/m².

For context, solar energy here swings from a low near 2.39 kWh/m² to a high of 5.06 kWh/m² in May across the year — June's 4.35 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.9Bright
24.9Bright
34.9Bright
44.8Bright
54.8Bright
64.7Bright
74.6Bright
84.6Bright
94.5Bright
104.5Bright
114.4Bright
124.4Bright
134.3Bright
144.3Bright
154.2Bright
164.2Bright
174.2Bright
184.2Bright
194.1Bright
204.1Bright
214.1Bright
224.1Bright
234.1Bright
244.1Bright
254.1Bright
264.1Bright
274.1Bright
284.1Bright
294.1Bright
304.1Bright
Planning a trip in June

Hazard calendar for Iwai

In seasonPeak

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

Iwai 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 June a good time to visit Iwai?

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

4.9
Sightseeing
4th-best month of the year
3.9
Beach & pool
4th-best month of the year

June is a reasonable time to visit Iwai for sightseeing.

What to pack for Iwai in June

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

In June, Iwai sees daytime highs around 23°C and nights near 17°C. Pack rain gear. Worth having: light clothes. About 20 days see rain.

rain gearlight clothes

Sea temperature near Iwai in June

The nearest coast averages about 21°C in June — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 60 km away) is warmest in August at about 26°C and coldest in February near 13°C.

It's comfortable for a long swim from Jun 7 to Nov 3 — about 4.9 months when the water holds above 20°C.

10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan14Bracing
Feb13Bracing
Mar13Bracing
Apr15Cool
May18Cool
Jun21Refreshing
Jul23Refreshing
Aug26Warm
Sep25Warm
Oct22Refreshing
Nov19Cool
Dec16Cool

UV index in Iwai in June

LowModerateHighVery highExtreme

Clear-sky midday UV in June 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 Iwai peaks around July 16 at about 10 (very high) — 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 highModerateJul 16UV 10Dec 23UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5Moderate
Apr7High
May9Very high
Jun9Very high
Jul10Very high
Aug9Very high
Sep9Very high
Oct6High
Nov4Moderate
Dec2Moderate

Air quality in Iwai in June

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Iwai is worst in April — around 26 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (December, 14 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateApr 1426 µg/m³Dec 1814 µg/m³
PM2.5 (µg/m³)Level
Jan15Moderate
Feb21Moderate
Mar25Moderate
Apr26Moderate
May24Moderate
Jun20Moderate
Jul17Moderate
Aug16Moderate
Sep16Moderate
Oct16Moderate
Nov16Moderate
Dec14Moderate
Location & terrain

Where is Iwai?

Iwai sits at 35.8°N, 139.2°E, 321 m above sea level, in Japan. The nearest listed city is Akiruno, 2.0 km away.

Topography around Iwai

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

Within 3 km, the terrain around Iwai has significant variations in elevation — a maximum elevation change of 387 m around an average of 279 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,339 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,737 m.

The land around Iwai is covered by trees (82%) within 3 km, trees (73%) and artificial surfaces (22%) within 16 km, and trees (48%) and artificial surfaces (27%) within 80 km.

3 km
387 m
16 km
1,339 m
80 km
3,737 m
treesgrasslandcroplandartificial surfacesbare terrainwater
June weather nearby: Akiruno 2.0 km · Itsukaichi 3.0 km · Ōme 4.0 km · Hamura 8.0 km · Fussa 8.0 km · Hakonegasaki 11 km · Hachiōji 13 km · Yokota 14 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 Iwai (35.75°, 139.2333°, elevation 321 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).