Uonuma weather in August

In August, Uonuma sees average daytime highs of 28°C and overnight lows near 21°C, with 180 mm of rain across 17.8 wet days and about 13.4 hours of daylight. It is the 1st-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 29°C in the first days to 27°C by the end. The sky is clear or mostly clear about 21% of the time in August, and the air most often feels muggy.

Daylight stretches from about 13 h 54 min at the start of August to 12 h 54 min by month's end. Set against the rest of the year, August is Uonuma's 2nd-clearest and 11th-windiest month. For the whole year in context, see Uonuma's year-round climate.

Daytime high
28°
1st warmest
Overnight low
21°
12th coldest
Rainfall
180 mm
17.8 wet days
Daylight
13 h 24 min
5:05 AM – 6:31 PM
Cloud cover
65%
2nd clearest
Wind
5 km/h
11th windiest
Solar energy
4.92 kWh/m²
Travel score
4.9
out of 10

Uonuma is city in Niigata Prefecture, Japan.

Density
36/km²
people per km²
Founded
2004

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

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 29°C in the first days to 27°C by the end.

A typical August day in Uonuma reaches about 28°C in the afternoon and slips back to 21°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 24°C and 32°C. Set against its neighbours, August runs about 2°C warmer than July and about 4°C warmer than September.

15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
12921
22921
32921
42921
52921
62921
72921
82921
92921
102921
112921
122921
132921
142921
152821
162821
172821
182821
192820
202820
212820
222820
232820
242820
252820
262820
272720
282720
292720
302719
312719

How August really feels in Uonuma

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.

Uonuma weather by month

How August compares with the rest of the year at a glance. August is the 1st-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -3°29826.224.19.70.0
Feb / -3°2232219.810.60.0
Mar / -1°20121.614.811.70.6
Apr14° / 14316.43.612.93.4
May20° / 10°152150.1145.5
Jun23° / 15°17816.6014.55.5
Jul27° / 20°26320.5014.34.7
Aug28° / 21°18017.8013.44.9
Sep24° / 17°19016.6012.35.5
Oct18° / 10°19616.60114.9
Nov12° / 19218.83.9102.5
Dec / -2°2712417.69.50.2

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

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

Beyond those clear spells, partly cloudy skies cover about 18% of August, with mostly cloudy or overcast conditions the remaining 61%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14060
24060
34060
43961
53961
64060
74060
84060
93961
103961
114060
123862
133862
143862
153961
163961
173961
184060
194060
204060
214060
224060
234060
243961
253961
263961
273862
283763
293763
303763
313763

Chance of precipitation in August

Any precipitation

Uonuma gets around 180 mm of rain over 17.8 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 57% and peaks near 60% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%151015202531
Rain chance (%)
153
253
353
453
553
653
754
854
954
1055
1155
1256
1356
1457
1558
1658
1759
1859
1959
2060
2160
2260
2360
2460
2560
2660
2760
2859
2959
3059
3159

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, August lands in the muggy band about 48% of days. Sticky, muggy-or-worse air turns up on roughly 85% of them.

0%25%50%75%100%151015202531
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1074745
2074746
3074746
4074746
5074746
6074646
7174646
8174646
9174646
10174646
11174646
12184645
13184645
14184644
15294643
16294642
172104641
182114640
192124739
203134737
213144735
223154834
233174931
243184929
253195127
263215125
274225123
284245121
294255219
305265217
315275216

Wind in August

Winds average 5 km/h in August.

Across August, daily wind ranges from about 5 km/h on the calmest days to 5 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (km/h)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm
315calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 13 h 54 min 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 60 minutes over August. Sunrise moves from 4:52 AM to 5:18 AM, and sunset from 6:48 PM to 6:11 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.94:526:48
213.94:536:47
313.94:546:46
413.84:556:45
513.84:566:44
613.84:566:43
713.74:576:42
813.74:586:41
913.74:596:40
1013.65:006:39
1113.65:016:38
1213.65:026:36
1313.55:026:35
1413.55:036:34
1513.55:046:33
1613.45:056:31
1713.45:066:30
1813.45:076:29
1913.35:086:28
2013.35:086:26
2113.35:096:25
2213.25:106:24
2313.25:116:22
2413.15:126:21
2513.15:136:19
2613.15:146:18
2713.05:146:16
2813.05:156:15
2913.05:166:13
3012.95:176:12
3112.95:186:11

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 4.92 kWh/m².

For context, solar energy here swings from a low near 1.87 kWh/m² to a high of 5.55 kWh/m² in May across the year — August's 4.92 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.3Bright
45.2Bright
55.2Bright
65.2Bright
75.2Bright
85.2Bright
95.1Bright
105.1Bright
115.1Bright
125.0Bright
135.0Bright
145.0Bright
154.9Bright
164.9Bright
174.9Bright
184.8Bright
194.8Bright
204.8Bright
214.7Bright
224.7Bright
234.7Bright
244.6Bright
254.6Bright
264.6Bright
274.5Bright
284.5Bright
294.5Bright
304.4Bright
314.4Bright
Planning a trip in August

Hazard calendar for Uonuma

In seasonPeak

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

Uonuma 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 August a good time to visit Uonuma?

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

4.9
Sightseeing
4th-best month of the year
5.6
Beach & pool
1st-best month of the year

August is a reasonable time to visit Uonuma for sightseeing.

What to pack for Uonuma in August

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

In August, Uonuma sees daytime highs around 28°C and nights near 21°C. Pack light clothes and rain gear. Worth having: sun protection. About 18 days see rain.

light clothesrain gearsun protection

Sea temperature near Uonuma in August

The nearest coast averages about 27°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 33 km away) is warmest in August at about 27°C and coldest in March near 10°C.

It's comfortable for a long swim from Jun 21 to Oct 31 — about 4.4 months when the water holds above 20°C.

10°20°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan12Bracing
Feb11Bracing
Mar10Bracing
Apr11Bracing
May15Bracing
Jun20Cool
Jul23Refreshing
Aug27Warm
Sep25Warm
Oct22Refreshing
Nov18Cool
Dec15Cool

UV index in Uonuma in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August 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 Uonuma peaks around August 12 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 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 highModerateAug 12UV 10Dec 21UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5Moderate
Apr7High
May8Very high
Jun9Very high
Jul10Very high
Aug10Very high
Sep8Very high
Oct5High
Nov3Moderate
Dec2Moderate

Air quality in Uonuma 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 Uonuma is worst in April — around 23 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (December, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1723 µg/m³Dec 1610 µg/m³
PM2.5 (µg/m³)Level
Jan12Good
Feb15Moderate
Mar22Moderate
Apr23Moderate
May22Moderate
Jun19Moderate
Jul17Moderate
Aug14Moderate
Sep12Moderate
Oct12Good
Nov11Good
Dec10Good
Location & terrain

Where is Uonuma?

Uonuma sits at 37.2°N, 139.0°E, 95 m above sea level, in Japan. The nearest listed city is Ojiya, 16 km away.

Topography around Uonuma

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

Within 3 km, the terrain around Uonuma has significant variations in elevation — a maximum elevation change of 251 m around an average of 138 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,713 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,554 m.

The land around Uonuma is covered by trees (43%), cropland (29%) and artificial surfaces (21%) within 3 km, trees (82%) within 16 km, and trees (70%) within 80 km.

3 km
251 m
16 km
1,713 m
80 km
2,554 m
treesgrasslandcroplandartificial surfaceswater
August weather nearby: Ojiya 16 km · Minamiuonuma 20 km · Muikamachi 21 km · Tōkamachi 21 km · Nagaoka 25 km · Shiozawa 25 km · Tochio-honchō 26 km · Mitsuke 32 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 Uonuma (37.2449°, 138.9623°, elevation 95 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).