Yanai weather in December

In December, Yanai sees average daytime highs of 12°C and overnight lows near 7°C, with 68 mm of precipitation across 9 wet days and about 9.8 hours of daylight. It is the 10th-warmest and 11th-wettest month of the year here.

Highs ease over the month, from about 13°C in the first days to 10°C by the end. The sky is clear or mostly clear about 32% 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 Yanai's 3rd-clearest and 2nd-windiest month. For the whole year in context, see Yanai's year-round climate.

Daytime high
12°
10th warmest
Overnight low
3rd coldest
Precipitation
68 mm
9 wet days
Daylight
9 h 42 min
7:15 AM – 5:00 PM
Cloud cover
54%
3rd clearest
Wind
17 km/h
2nd windiest
Solar energy
2.33 kWh/m²
Travel score
3.2
out of 10

Yanai is city in Yamaguchi Prefecture, Japan.

Density
232/km²
people per km²
Founded
2005

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 13°C in the first days to 10°C by the end.

A typical December day in Yanai reaches about 12°C in the afternoon and slips back to 7°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 8°C and 15°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)
1149
2149
3149
4139
5139
6139
7138
8138
9128
10128
11128
12128
13128
14127
15127
16117
17117
18117
19117
20117
21117
22117
23117
24116
25116
26116
27106
28106
29106
30106
31106

How December really feels in Yanai

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.

Yanai weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 588.10.8101.9
Feb10° / 748.80.810.72.1
Mar12° / 1229.90.111.73.4
Apr16° / 12°1469.9012.85.2
May20° / 16°16710013.76.3
Jun23° / 20°25313.5014.26.0
Jul27° / 24°23913.80145.6
Aug29° / 25°14311.5013.35.5
Sep26° / 22°16911.2012.26.5
Oct22° / 17°1207.7011.17.1
Nov17° / 12°767.8010.25.7
Dec12° / 6890.29.83.2

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 32% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 24% of December, with mostly cloudy or overcast conditions the remaining 44%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15941
25941
35941
45941
55842
65743
75743
85743
95644
105644
115644
125644
135644
145644
155545
165545
175545
185545
195446
205446
215545
225545
235545
245545
255644
265644
275644
285644
295644
305644
315644

Chance of precipitation in December

Any precipitation

Yanai gets around 68 mm of rain and snow over 9 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 28% and peaks near 30% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%151015202531
Rain chance (%)
129
229
329
430
530
630
730
830
930
1029
1129
1229
1329
1428
1528
1628
1728
1827
1927
2027
2127
2227
2327
2427
2527
2627
2726
2826
2926
3025
3125

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 (%)
19631
29631
39631
49721
59721
69820
79910
89910
99910
109910
119910
129910
139910
149910
159910
169910
179910
189910
1910000
2010000
2110000
2210000
2310000
2410000
2510000
2610000
2710000
2810000
2910000
3010000
3110000

Wind in December

Winds average 17 km/h in December.

Across December, daily wind ranges from about 16 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
116light breeze
216light breeze
316light breeze
416light breeze
516light breeze
616light breeze
716light breeze
816light breeze
917light breeze
1017light breeze
1117light breeze
1217light breeze
1317light breeze
1417light breeze
1517light breeze
1617light breeze
1717light breeze
1817light breeze
1917light breeze
2017light breeze
2117light breeze
2217light breeze
2317light breeze
2417light breeze
2517light breeze
2617light breeze
2718light breeze
2818light breeze
2918light breeze
3018light breeze
3118light 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 7:04 AM to 7:22 AM, and sunset from 4:58 PM to 5:08 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.97:044:58
29.97:054:58
39.97:064:58
49.97:074:58
59.87:074:58
69.87:084:58
79.87:094:58
89.87:104:58
99.87:114:59
109.87:114:59
119.87:124:59
129.87:134:59
139.87:134:59
149.87:145:00
159.87:155:00
169.77:155:00
179.77:165:01
189.77:165:01
199.77:175:01
209.77:175:02
219.77:185:02
229.77:185:03
239.77:195:03
249.77:195:04
259.77:205:04
269.77:205:05
279.77:205:05
289.77:215:06
299.87:215:06
309.87:215:07
319.87:225:08

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.33 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.33 kWh/m² to a high of 5.51 kWh/m² in May across the year — December's 2.33 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
12.5Moderate
22.4Moderate
32.4Moderate
42.4Moderate
52.4Moderate
62.4Moderate
72.4Moderate
82.4Moderate
92.3Moderate
102.3Moderate
112.3Moderate
122.3Moderate
132.3Moderate
142.3Moderate
152.3Moderate
162.3Moderate
172.3Moderate
182.3Moderate
192.3Moderate
202.3Moderate
212.3Moderate
222.3Moderate
232.3Moderate
242.4Moderate
252.4Moderate
262.4Moderate
272.4Moderate
282.4Moderate
292.4Moderate
302.4Moderate
312.4Moderate
Planning a trip in December

Hazard calendar for Yanai

In seasonPeak

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

Yanai 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 December a good time to visit Yanai?

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

3.2
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 Yanai.

What to pack for Yanai in December

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

In December, Yanai sees daytime highs around 12°C and nights near 7°C. Pack a warm layer. Worth having: rain gear. About 9 days see rain.

a warm layerrain gear

Sea temperature near Yanai in December

The nearest coast averages about 17°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 25 km away) is warmest in August at about 27°C and coldest in February near 13°C.

It's comfortable for a long swim from Jun 9 to Nov 16 — about 5.3 months when the water holds above 20°C.

10°15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan14Bracing
Feb13Bracing
Mar13Bracing
Apr15Bracing
May17Cool
Jun21Refreshing
Jul25Warm
Aug27Warm
Sep25Warm
Oct23Refreshing
Nov20Refreshing
Dec17Cool

UV index in Yanai 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 Yanai peaks around June 23 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 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 highModerateJun 23UV 10Dec 21UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar6High
Apr7Very high
May8Very high
Jun10Very high
Jul10Very high
Aug9Very high
Sep9Very high
Oct6High
Nov4Moderate
Dec3Moderate

Air quality in Yanai 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 Yanai is worst in April — around 23 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (October, 11 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateModerateApr 1323 µg/m³Oct 1612 µg/m³
PM2.5 (µg/m³)Level
Jan15Moderate
Feb18Moderate
Mar23Moderate
Apr23Moderate
May22Moderate
Jun19Moderate
Jul17Moderate
Aug16Moderate
Sep13Moderate
Oct11Good
Nov13Moderate
Dec13Moderate
Location & terrain

Where is Yanai?

Yanai sits at 34.0°N, 132.1°E, 0 m above sea level, in Japan. The nearest listed city is Hikari, 15 km away.

Topography around Yanai

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

Within 3 km, the terrain around Yanai has significant variations in elevation — a maximum elevation change of 525 m around an average of 91 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 682 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,334 m.

The land around Yanai is covered by trees (59%) and artificial surfaces (23%) within 3 km, trees (56%) and water (32%) within 16 km, and trees (49%) and water (45%) within 80 km.

3 km
525 m
16 km
682 m
80 km
1,334 m
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Hikari 15 km · Kudamatsu 24 km · Iwakuni 24 km · Ōtake 28 km · Tokuyama 29 km · Shūnan 30 km · Ōno-hara 38 km · Miyajima 42 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 Yanai (33.9667°, 132.1167°, elevation 0 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).