Koga weather in August

In August, Koga sees average daytime highs of 30°C and overnight lows near 23°C, with 161 mm of rain across 16.3 wet days and about 13.4 hours of daylight. It is the 1st-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 31°C in the first days to 29°C by the end. 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 13 h 54 min at the start of August to 12 h 48 min by month's end. Set against the rest of the year, August is Koga's 9th-clearest and 9th-windiest month. For the whole year in context, see Koga's year-round climate.

Daytime high
30°
1st warmest
Overnight low
23°
12th coldest
Rainfall
161 mm
16.3 wet days
Daylight
13 h 24 min
5:04 AM – 6:27 PM
Cloud cover
69%
9th clearest
Wind
7 km/h
9th windiest
Solar energy
4.46 kWh/m²
Travel score
4.1
out of 10

Koga is city in Ibaraki Prefecture, Japan.

Density
1,128/km²
people per km²
Founded
2005

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 31°C in the first days to 29°C by the end.

A typical August day in Koga reaches about 30°C in the afternoon and slips back to 23°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 26°C and 34°C. Set against its neighbours, August runs about 1°C warmer than July and about 4°C warmer than September.

15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
13124
23124
33124
43124
53124
63124
73124
83124
93124
103124
113124
123124
133124
143124
153124
163124
173023
183023
193023
203023
213023
223023
233023
243023
253023
263023
272923
282923
292923
302923
312922

How August really feels in Koga

Once humidity and wind are folded in, August averages 27 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
27
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in August is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Koga weather by month

How August compares with the rest of the year at a glance. August is the 1st-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -0°5561.89.81.7
Feb / 546.92.210.62.1
Mar13° / 10611.61.311.73.5
Apr18° / 12012.60.212.95.4
May23° / 14°15313.7013.96.1
Jun25° / 18°17716.5014.45.3
Jul29° / 22°20918.7014.24.3
Aug30° / 23°16116.3013.44.1
Sep26° / 20°20616.2012.25.3
Oct21° / 14°20013.9011.15.9
Nov16° / 889.4010.15.0
Dec11° / 546.80.49.62.9

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 17% of August, with mostly cloudy or overcast conditions the remaining 65%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13466
23565
33565
43565
53664
63664
73565
83664
93664
103664
113565
123565
133565
143664
153565
163565
173565
183565
193466
203565
213565
223565
233565
243565
253565
263565
273565
283565
293565
303565
313664

Chance of precipitation in August

Any precipitation

Koga gets around 161 mm of rain over 16.3 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 53% and peaks near 54% 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
2853
2953
3054
3154

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 55% of days. Sticky, muggy-or-worse air turns up on roughly 93% of them.

0%25%50%75%100%151015202531
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
106135724
205135824
305135725
405135725
505135725
605135725
705135824
805145724
905145724
1005145823
1115155623
1215155722
1315165622
1415165721
1515175720
1615175720
1726185519
1826195518
1926205517
2026215417
2127225316
2227235315
2327245413
2427255412
2528265311
2628285210
2718295210
281930519
291931518
301932517
3111034497

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 7 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
307calm
317calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 13 h 54 min at the start of August to 12 h 48 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 4:51 AM to 5:16 AM, and sunset from 6:43 PM to 6:06 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.94:516:43
213.84:526:42
313.84:536:41
413.84:546:40
513.74:556:39
613.74:556:38
713.74:566:37
813.64:576:36
913.64:586:35
1013.64:596:34
1113.65:006:33
1213.55:006:32
1313.55:016:30
1413.55:026:29
1513.45:036:28
1613.45:046:27
1713.45:046:26
1813.35:056:24
1913.35:066:23
2013.25:076:22
2113.25:086:20
2213.25:096:19
2313.15:096:18
2413.15:106:16
2513.15:116:15
2613.05:126:14
2713.05:136:12
2813.05:136:11
2912.95:146:09
3012.95:156:08
3112.85:166:06

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 4.46 kWh/m².

For context, solar energy here swings from a low near 2.38 kWh/m² to a high of 5.07 kWh/m² in May across the year — August's 4.46 kWh/m² sits near the top of that range.

024151015202531
Solar energy (kWh/m²)Level
14.8Bright
24.8Bright
34.8Bright
44.8Bright
54.7Bright
64.7Bright
74.7Bright
84.7Bright
94.7Bright
104.6Bright
114.6Bright
124.6Bright
134.5Bright
144.5Bright
154.5Bright
164.4Bright
174.4Bright
184.4Bright
194.3Bright
204.3Bright
214.3Bright
224.3Bright
234.2Bright
244.2Bright
254.2Bright
264.1Bright
274.1Bright
284.1Bright
294.0Bright
304.0Bright
314.0Bright
Planning a trip in August

Is August a good time to visit Koga?

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

4.1
Sightseeing
8th-best month of the year
5.7
Beach & pool
1st-best month of the year

August is a reasonable time to visit Koga for sightseeing.

What to pack for Koga in August

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

In August, Koga sees daytime highs around 30°C and nights near 23°C. Pack light clothes and rain gear. About 16 days see rain.

light clothesrain gear

Sea temperature near Koga in August

The nearest coast averages about 26°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 64 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 Koga 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 Koga peaks around July 16 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 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 10Jan 1UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar4Moderate
Apr6High
May8Very high
Jun9Very high
Jul10Very high
Aug9Very high
Sep9Very high
Oct6High
Nov3Moderate
Dec2Moderate

Air quality in Koga 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 Koga 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 Koga?

Koga sits at 36.2°N, 139.7°E, 17 m above sea level, in Japan. The nearest listed city is Nogi, 5.0 km away.

Topography around Koga

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

Within 3 km, the terrain around Koga has only modest variations in elevation — a maximum elevation change of 27 m around an average of 17 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 197 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,553 m.

The land around Koga is covered by artificial surfaces (57%) and cropland (26%) within 3 km, cropland (49%) and artificial surfaces (33%) within 16 km, and trees (46%), artificial surfaces (27%) and cropland (20%) within 80 km.

3 km
27 m
16 km
197 m
80 km
2,553 m
treesgrasslandcroplandartificial surfaceswaterwetland
August weather nearby: Nogi 5.0 km · Kurihashi 6.0 km · Fujioka 10 km · Washinomiya 11 km · Sakai 12 km · Satte 12 km · Kazo 13 km · Kukichūō 13 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 Koga (36.1833°, 139.7167°, elevation 17 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. 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).