Ōmachi weather in August

In August, Ōmachi sees average daytime highs of 23°C and overnight lows near 16°C, with 297 mm of rain across 21.9 wet days and about 13.4 hours of daylight. It is the 1st-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 24°C in the first days to 22°C by the end. The sky is clear or mostly clear about 10% of the time in August, and the air most often feels humid.

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 Ōmachi's 8th-clearest and 12th-windiest month. For the whole year in context, see Ōmachi's year-round climate.

Daytime high
23°
1st warmest
Overnight low
16°
12th coldest
Rainfall
297 mm
21.9 wet days
Daylight
13 h 24 min
5:11 AM – 6:35 PM
Cloud cover
74%
8th clearest
Wind
4 km/h
12th windiest
Solar energy
4.99 kWh/m²
Travel score
4.9
out of 10

Ōmachi is dissolved municipality in Kitaazumi district, Nagano prefecture, Japan.

Founded
1889

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 24°C in the first days to 22°C by the end.

A typical August day in Ōmachi reaches about 23°C in the afternoon and slips back to 16°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 20°C and 26°C. Set against its neighbours, August runs about 1°C warmer than July and about 4°C warmer than September.

10°15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
12417
22417
32417
42417
52417
62417
72417
82417
92417
102417
112417
122417
132416
142316
152316
162316
172316
182316
192316
202316
212316
222316
232316
242316
252315
262215
272215
282215
292215
302215
312215

How August really feels in Ōmachi

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.

Ōmachi 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-5° / -11°19322.4249.80.0
Feb-3° / -10°16718.319.610.60.0
Mar / -6°2111919.111.70.0
Apr / -1°20016.69.912.90.9
May14° / 23717.81.313.93.5
Jun18° / 11°34420.6014.44.1
Jul22° / 15°45124.4014.24.3
Aug23° / 16°29721.9013.44.9
Sep19° / 12°29219.1012.24.6
Oct13° / 22716.31.111.13.2
Nov / -2°18317.311.110.10.6
Dec-2° / -8°19621.421.49.60.0

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 10% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 17% of August, with mostly cloudy or overcast conditions the remaining 73%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
12872
22872
32971
42872
52872
62872
72773
82773
92773
102773
112773
122773
132773
142773
152773
162773
172674
182674
192773
202773
212674
222773
232773
242773
252674
262674
272674
282674
292575
302575
312575

Chance of precipitation in August

Any precipitation

Ōmachi gets around 297 mm of rain over 21.9 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 71% and peaks near 72% on the wettest days.

0%20%40%60%80%151015202531
Rain chance (%)
172
272
371
471
571
671
770
870
970
1070
1170
1270
1370
1470
1570
1670
1770
1870
1970
2070
2170
2270
2371
2471
2571
2672
2772
2872
2972
3072
3172

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, August lands in the humid band about 59% of days. Sticky, muggy-or-worse air turns up on roughly 6% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
1226666
2225676
3225676
4224686
5224686
6224677
7224677
8223687
9223687
10223678
11223678
12324658
13324658
14325648
15426628
16426628
17527608
18528607
19630577
20731557
21732556
22833536
23934525
241035505
251136494
261237484
271338463
281438453
291539432
301740422
311840402

Wind in August

Winds average 4 km/h in August, the calmest month.

Across August, daily wind ranges from about 4 km/h on the calmest days to 4 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (km/h)Feels
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm
314calm

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 4:58 AM to 5:23 AM, and sunset from 6:51 PM to 6:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.94:586:51
213.94:596:50
313.85:006:49
413.85:016:48
513.85:016:47
613.75:026:46
713.75:036:45
813.75:046:44
913.65:056:43
1013.65:066:42
1113.65:066:41
1213.55:076:40
1313.55:086:38
1413.55:096:37
1513.45:106:36
1613.45:116:35
1713.45:116:33
1813.35:126:32
1913.35:136:31
2013.35:146:30
2113.25:156:28
2213.25:166:27
2313.25:166:26
2413.15:176:24
2513.15:186:23
2613.05:196:21
2713.05:206:20
2813.05:206:19
2912.95:216:17
3012.95:226:16
3112.95:236:14

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 4.99 kWh/m².

For context, solar energy here swings from a low near 2.39 kWh/m² to a high of 5.74 kWh/m² in May across the year — August's 4.99 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.3Bright
45.3Bright
55.3Bright
65.3Bright
75.2Bright
85.2Bright
95.2Bright
105.2Bright
115.1Bright
125.1Bright
135.1Bright
145.0Bright
155.0Bright
165.0Bright
174.9Bright
184.9Bright
194.9Bright
204.8Bright
214.8Bright
224.8Bright
234.8Bright
244.7Bright
254.7Bright
264.7Bright
274.6Bright
284.6Bright
294.5Bright
304.5Bright
314.5Bright
Planning a trip in August

Hazard calendar for Ōmachi

In seasonPeak

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

Ōmachi 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 Ōmachi?

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

4.9
Sightseeing
1st-best month of the year
3.8
Beach & pool
1st-best month of the year

August is a reasonable time to visit Ōmachi for sightseeing.

What to pack for Ōmachi in August

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

In August, Ōmachi sees daytime highs around 23°C and nights near 16°C. Pack rain gear. Worth having: light clothes and sun protection. About 22 days see rain.

rain gearlight clothessun protection

Sea temperature near Ōmachi 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 61 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 18 to Nov 3 — about 4.6 months when the water holds above 20°C.

10°20°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan13Bracing
Feb11Bracing
Mar10Bracing
Apr11Bracing
May15Cool
Jun20Cool
Jul24Refreshing
Aug27Warm
Sep25Warm
Oct22Refreshing
Nov19Cool
Dec16Cool

UV index in Ōmachi 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 Ōmachi peaks around July 20 at about 10 (extreme) — 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 highExtremeVery highModerateJul 20UV 10Dec 21UV 2
UV index (midday)Level
Jan3Moderate
Feb5Moderate
Mar6High
Apr7Very high
May9Very high
Jun10Very high
Jul10Extreme
Aug10Extreme
Sep9Very high
Oct6High
Nov3Moderate
Dec2Moderate

Air quality in Ōmachi 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 Ōmachi is worst in April — around 21 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (December, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1721 µg/m³Dec 1510 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar20Moderate
Apr21Moderate
May20Moderate
Jun18Moderate
Jul15Moderate
Aug13Moderate
Sep12Good
Oct11Good
Nov11Good
Dec10Good
Location & terrain

Where is Ōmachi?

Ōmachi sits at 36.5°N, 137.9°E, 714 m above sea level, in Japan. The nearest listed city is Hotaka, 18 km away.

Topography around Ōmachi

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

Within 3 km, the terrain around Ōmachi has significant variations in elevation — a maximum elevation change of 486 m around an average of 823 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 2,371 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,120 m.

The land around Ōmachi is covered by trees (50%) and artificial surfaces (26%) within 3 km, trees (83%) within 16 km, and trees (75%) within 80 km.

3 km
486 m
16 km
2,371 m
80 km
3,120 m
treesgrasslandcroplandartificial surfacesbare terrainwater
August weather nearby: Hotaka 18 km · Chikuma 20 km · Toyoshina 22 km · Azumino 24 km · Sakaki 29 km · Matsumoto 31 km · Nagano 33 km · Ueda 39 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 Ōmachi (36.5°, 137.8667°, elevation 714 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).