Koga weather in December

In December, Koga sees average daytime highs of 12°C and overnight lows near 6°C, with 66 mm of precipitation across 9.2 wet days and about 9.8 hours of daylight. It is the 10th-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 14°C in the first days to 11°C by the end. The sky is clear or mostly clear about 21% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 54 min at the start of December to 9 h 48 min by month's end. Set against the rest of the year, December is Koga's 7th-clearest and 4th-windiest month. For the whole year in context, see Koga's year-round climate.

Daytime high
12°
10th warmest
Overnight low
3rd coldest
Precipitation
66 mm
9.2 wet days
Daylight
9 h 48 min
7:21 AM – 5:07 PM
Cloud cover
63%
7th clearest
Wind
12 km/h
4th windiest
Solar energy
2.14 kWh/m²
Travel score
3.4
out of 10

Koga is city in Fukuoka Prefecture, Japan.

Density
1,397/km²
people per km²
Founded
1997

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 14°C in the first days to 11°C by the end.

A typical December day in Koga reaches about 12°C in the afternoon and slips back to 6°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 8°C and 16°C. Set against its neighbours, December runs about 5°C cooler than November and about 3°C warmer than January.

10°15°20°151015202531
Avg high (°C)Avg low (°C)
1158
2148
3148
4147
5147
6147
7137
8137
9137
10136
11136
12136
13126
14126
15126
16126
17126
18126
19125
20125
21125
22125
23125
24125
25115
26115
27115
28115
29115
30115
31115

How December really feels in Koga

Once humidity and wind are folded in, December 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

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

Koga weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan10° / 629.91.2102.2
Feb11° / 659.20.810.72.7
Mar14° / 10811.30.211.74.1
Apr19° / 11°11910.5012.86.0
May24° / 16°13110013.76.8
Jun27° / 20°25314.3014.25.6
Jul30° / 24°249160144.0
Aug32° / 25°15514.5013.33.6
Sep28° / 22°17412.8012.25.5
Oct23° / 16°957.6011.27.3
Nov18° / 11°828.4010.25.9
Dec12° / 669.20.39.83.4

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

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

Beyond those clear spells, partly cloudy skies cover about 20% of December, with mostly cloudy or overcast conditions the remaining 59%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14951
24852
34852
44753
54753
64654
74456
84555
94456
104357
114357
124258
134159
144060
154060
163961
173862
183862
193862
203763
213763
223763
233763
243763
253862
263763
273763
283763
293763
303763
313763

Chance of precipitation in December

Any precipitationSnow

Koga gets around 66 mm of rain and snow over 9.2 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 29% and peaks near 31% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
1300
2310
3310
4310
5300
6301
7301
8301
9301
10301
11301
12301
13301
14301
15301
16301
17301
18301
19301
20301
21301
22291
23291
24291
25291
26282
27282
28272
29272
30272
31263

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the dry band about 99% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)
19541
29730
39730
49730
59820
69820
79820
89910
99910
109910
119910
129910
139910
149910
1510000
1610000
1710000
1810000
1910000
2010000
2110000
2210000
2310000
2410000
2510000
2610000
2710000
2810000
2910000
3010000
3110000

Wind in December

Winds average 12 km/h in December.

Across December, daily wind ranges from about 11 km/h on the calmest days to 12 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
111calm
211calm
311calm
411calm
511calm
611calm
711calm
811calm
912calm
1012calm
1112calm
1212calm
1312calm
1412calm
1512calm
1612calm
1712calm
1812calm
1912calm
2012calm
2112calm
2212light breeze
2312light breeze
2412light breeze
2512light breeze
2612light breeze
2712light breeze
2812light breeze
2912light breeze
3012light breeze
3112light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 54 min at the start of December to 9 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over December. Sunrise moves from 7:10 AM to 7:28 AM, and sunset from 5:06 PM to 5:15 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.97:105:06
29.97:115:05
39.97:125:05
49.97:135:05
59.97:145:05
69.97:145:05
79.87:155:06
89.87:165:06
99.87:175:06
109.87:175:06
119.87:185:06
129.87:195:06
139.87:195:07
149.87:205:07
159.87:215:07
169.87:215:07
179.87:225:08
189.87:225:08
199.87:235:08
209.87:235:09
219.87:245:09
229.87:245:10
239.87:255:10
249.87:255:11
259.87:265:11
269.87:265:12
279.87:265:12
289.87:275:13
299.87:275:14
309.87:275:14
319.87:285:15

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.14 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.14 kWh/m² to a high of 5.51 kWh/m² in May across the year — December's 2.14 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
12.3Moderate
22.3Moderate
32.3Moderate
42.2Moderate
52.2Moderate
62.2Moderate
72.2Moderate
82.2Moderate
92.2Moderate
102.1Moderate
112.1Moderate
122.1Moderate
132.1Moderate
142.1Moderate
152.1Moderate
162.1Moderate
172.1Moderate
182.1Moderate
192.1Moderate
202.1Moderate
212.1Moderate
222.1Moderate
232.1Moderate
242.1Moderate
252.2Moderate
262.2Moderate
272.2Moderate
282.2Moderate
292.2Moderate
302.2Moderate
312.2Moderate
Planning a trip in December

Hazard calendar for Koga

In seasonPeak

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

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

Koga's rainy season runs April–September, 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 December a good time to visit Koga?

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

3.4
Sightseeing
10th-best month of the year
0.0
Beach & pool
10th-best month of the year

December is a weaker month for outdoor sightseeing in Koga.

What to pack for Koga in December

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

In December, Koga sees daytime highs around 12°C and nights near 6°C. Worth packing: a warm layer and rain gear. About 9 days see rain.

a warm layerrain gear

Sea temperature near Koga in December

The nearest coast averages about 18°C in December — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 18 km away) is warmest in August at about 27°C and coldest in February near 14°C.

It's comfortable for a long swim from Jun 7 to Nov 20 — about 5.5 months when the water holds above 20°C.

10°15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan16Cool
Feb14Bracing
Mar14Bracing
Apr15Cool
May18Cool
Jun21Refreshing
Jul25Warm
Aug27Warm
Sep26Warm
Oct23Refreshing
Nov20Refreshing
Dec18Cool

UV index in Koga in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 3. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Koga peaks around July 21 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJul 21UV 9Dec 22UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar6High
Apr8Very high
May8Very high
Jun7Very high
Jul9Very high
Aug9Very high
Sep9Very high
Oct6High
Nov4Moderate
Dec3Moderate

Air quality in Koga in December

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Koga is worst in April — around 25 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (October, 12 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateApr 1225 µg/m³Oct 1212 µg/m³
PM2.5 (µg/m³)Level
Jan17Moderate
Feb20Moderate
Mar25Moderate
Apr25Moderate
May23Moderate
Jun18Moderate
Jul13Moderate
Aug15Moderate
Sep13Moderate
Oct12Moderate
Nov15Moderate
Dec14Moderate
Location & terrain

Where is Koga?

Koga sits at 33.7°N, 130.5°E, 10 m above sea level, in Japan. The nearest listed city is Nishifukuma, 4.0 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 108 m around an average of 13 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 674 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,246 m.

The land around Koga is covered by artificial surfaces (43%) and water (30%) within 3 km, water (42%) and trees (32%) within 16 km, and water (51%) and trees (34%) within 80 km.

3 km
108 m
16 km
674 m
80 km
1,246 m
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Nishifukuma 4.0 km · Shingū 4.0 km · Fukutsu 6.0 km · Munakata 11 km · Wakasugi 15 km · Sasaguri 15 km · Fukuoka 16 km · Sue 16 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 (33.7333°, 130.4667°, elevation 10 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).