Iwanuma weather in August

In August, Iwanuma sees average daytime highs of 26°C and overnight lows near 21°C, with 174 mm of rain across 16.4 wet days and about 13.5 hours of daylight. It is the 1st-warmest and 3rd-wettest month of the year here.

Day-to-day highs hold fairly steady near 26°C through the month. The sky is clear or mostly clear about 18% of the time in August, and the air most often feels oppressive.

Daylight stretches from about 14 hours at the start of August to 12 h 54 min by month's end. Set against the rest of the year, August is Iwanuma's 10th-clearest and 11th-windiest month. For the whole year in context, see Iwanuma's year-round climate.

Daytime high
26°
1st warmest
Overnight low
21°
12th coldest
Rainfall
174 mm
16.4 wet days
Daylight
13 h 30 min
4:56 AM – 6:25 PM
Cloud cover
72%
10th clearest
Wind
7 km/h
11th windiest
Solar energy
4.28 kWh/m²
Travel score
5.5
out of 10

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 26°C through the month.

A typical August day in Iwanuma reaches about 26°C in the afternoon and slips back to 21°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 30°C. Set against its neighbours, August runs about 2°C warmer than July and about 3°C warmer than September.

15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
12721
22721
32722
42722
52722
62722
72722
82722
92722
102722
112722
122722
132722
142722
152621
162621
172621
182621
192621
202621
212621
222621
232621
242621
252621
262621
272621
282621
292621
302520
312520

How August really feels in Iwanuma

Once humidity and wind are folded in, August 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

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

Iwanuma weather by month

How August compares with the rest of the year at a glance. August is the 1st-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -1°599.26.79.70.0
Feb / -1°488.15.510.50.1
Mar / 8910.63.911.71.5
Apr14° / 10010.60.8133.8
May18° / 11°11011.70145.6
Jun21° / 16°13813.9014.65.6
Jul25° / 20°19618.1014.45.3
Aug26° / 21°17416.4013.55.5
Sep23° / 18°18114.3012.35.8
Oct18° / 12°157110115.7
Nov13° / 668.40.49.93.6
Dec / 529.549.40.9

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 18% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 13% of August, with mostly cloudy or overcast conditions the remaining 70%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13169
23169
33169
43169
53169
63070
73070
83070
93070
103070
112872
122872
132872
142872
152872
162872
172872
182971
193070
203070
213070
223070
233169
243169
253169
263268
273169
283268
293367
303367
313466

Chance of precipitation in August

Any precipitation

Iwanuma gets around 174 mm of rain over 16.4 wet days in August. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 52% and peaks near 53% on the wettest days.

0%20%40%60%151015202531
Rain chance (%)
151
251
351
451
551
651
751
852
952
1052
1153
1253
1353
1453
1553
1653
1753
1853
1953
2053
2153
2253
2353
2453
2553
2653
2753
2852
2952
3052
3152

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, August lands in the oppressive band about 48% of days. Sticky, muggy-or-worse air turns up on roughly 82% of them.

0%25%50%75%100%151015202531
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
131128553
231127563
331126564
431126564
531125574
631125574
731125565
831125565
931125565
1031125565
1131226545
1231227544
1331227544
1431228534
1531229524
1631230523
1731231513
1841232493
1941233483
2041334472
2141335462
2251435442
2351536432
2451636422
2551736402
2651737392
2751937382
2852037362
2962137352
3062237332
3162337322

Wind in August

Winds average 7 km/h in August.

Across August, daily wind ranges from about 7 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (km/h)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
308calm
318calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 hours at the start of August to 12 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 66 minutes over August. Sunrise moves from 4:43 AM to 5:09 AM, and sunset from 6:42 PM to 6:04 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.04:436:42
214.04:446:42
313.94:446:40
413.94:456:39
513.94:466:38
613.84:476:37
713.84:486:36
813.84:496:35
913.74:506:34
1013.74:516:33
1113.74:526:32
1213.64:526:30
1313.64:536:29
1413.64:546:28
1513.54:556:27
1613.54:566:25
1713.54:576:24
1813.44:586:23
1913.44:596:21
2013.35:006:20
2113.35:016:18
2213.35:016:17
2313.25:026:16
2413.25:036:14
2513.15:046:13
2613.15:056:11
2713.15:066:10
2813.05:076:08
2913.05:086:07
3012.95:096:05
3112.95:096:04

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 4.28 kWh/m².

For context, solar energy here swings from a low near 2.13 kWh/m² to a high of 5.36 kWh/m² in May across the year — August's 4.28 kWh/m² falls in the middle.

024151015202531
Solar energy (kWh/m²)Level
14.6Bright
24.6Bright
34.6Bright
44.6Bright
54.6Bright
64.6Bright
74.6Bright
84.5Bright
94.5Bright
104.5Bright
114.4Bright
124.4Bright
134.4Bright
144.3Bright
154.3Bright
164.3Bright
174.2Bright
184.2Bright
194.2Bright
204.1Bright
214.1Bright
224.1Bright
234.1Bright
244.0Bright
254.0Bright
264.0Moderate
274.0Moderate
283.9Moderate
293.9Moderate
303.9Moderate
313.9Moderate
Planning a trip in August

Hazard calendar for Iwanuma

In seasonPeak

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

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

Iwanuma'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 August a good time to visit Iwanuma?

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

5.5
Sightseeing
5th-best month of the year
5.4
Beach & pool
1st-best month of the year

August is a reasonable time to visit Iwanuma for sightseeing.

What to pack for Iwanuma in August

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

In August, Iwanuma sees daytime highs around 26°C and nights near 21°C. Pack rain gear. Worth having: light clothes. About 16 days see rain.

rain gearlight clothes

Sea temperature near Iwanuma in August

The nearest coast averages about 24°C in August — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 23 km away) is warmest in August at about 24°C and coldest in March near 9°C.

It's comfortable for a long swim from Jul 7 to Oct 10 — about 3.2 months when the water holds above 20°C.

5°10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan11Bracing
Feb9Bracing
Mar9Bracing
Apr10Bracing
May14Bracing
Jun18Cool
Jul21Refreshing
Aug24Refreshing
Sep23Refreshing
Oct19Cool
Nov17Cool
Dec14Bracing

UV index in Iwanuma in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August 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 Iwanuma peaks around August 13 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateAug 13UV 9Jan 10UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun8Very high
Jul9Very high
Aug9Very high
Sep8Very high
Oct5High
Nov3Moderate
Dec2Low

Air quality in Iwanuma in August

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Iwanuma is worst in April — around 21 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (December, 9 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1621 µg/m³Dec 1710 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar20Moderate
Apr21Moderate
May20Moderate
Jun14Moderate
Jul12Good
Aug10Good
Sep10Good
Oct11Good
Nov11Good
Dec9Good
Location & terrain

Where is Iwanuma?

Iwanuma sits at 38.1°N, 140.9°E, 5 m above sea level, in Japan. The nearest listed city is Natori-shi, 7.0 km away.

Topography around Iwanuma

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

Within 3 km, the terrain around Iwanuma has only modest variations in elevation — a maximum elevation change of 196 m around an average of 22 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 329 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,037 m.

The land around Iwanuma is covered by cropland (34%), artificial surfaces (33%) and trees (20%) within 3 km, trees (32%), water (25%) and cropland (21%) within 16 km, and trees (56%) and water (27%) within 80 km.

3 km
196 m
16 km
329 m
80 km
2,037 m
treesgrasslandcroplandartificial surfacesbare terrainwater
August weather nearby: Natori-shi 7.0 km · Watari 8.0 km · Murata 12 km · Ōkawara 13 km · Kakuda 16 km · Sendai 18 km · Shiroishi 24 km · Tagajō-shi 25 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 Iwanuma (38.1047°, 140.8594°, 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).