Isa weather in December

In December, Isa sees average daytime highs of 13°C and overnight lows near 5°C, with 90 mm of precipitation across 8.7 wet days and about 9.9 hours of daylight. It is the 10th-warmest and 11th-wettest month of the year here.

Highs ease over the month, from about 15°C in the first days to 12°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 10 h 06 min at the start of December to 9 h 54 min by month's end. Set against the rest of the year, December is Isa's 3rd-clearest and 3rd-windiest month. For the whole year in context, see Isa's year-round climate.

Daytime high
13°
10th warmest
Overnight low
3rd coldest
Precipitation
90 mm
8.7 wet days
Daylight
9 h 54 min
7:16 AM – 5:11 PM
Cloud cover
55%
3rd clearest
Wind
10 km/h
3rd windiest
Solar energy
2.42 kWh/m²
Travel score
3.7
out of 10

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 15°C in the first days to 12°C by the end.

A typical December day in Isa reaches about 13°C in the afternoon and slips back to 5°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 17°C. Set against its neighbours, December runs about 5°C cooler than November and about 2°C warmer than January.

10°15°20°151015202531
Avg high (°C)Avg low (°C)
1158
2157
3157
4157
5147
6147
7146
8146
9146
10136
11136
12136
13136
14135
15135
16135
17135
18125
19125
20125
21125
22125
23125
24125
25125
26124
27124
28124
29124
30124
31114

How December really feels in Isa

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.

Isa 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
Jan11° / 829.80.810.12.6
Feb12° / 1069.60.410.83.1
Mar15° / 15113.20.111.84.3
Apr20° / 11°18412.1012.85.8
May23° / 16°20912.3013.66.3
Jun26° / 20°52819.6014.14.9
Jul30° / 24°37320.1013.93.9
Aug31° / 24°18417.2013.23.8
Sep28° / 21°19414.3012.25.3
Oct24° / 16°1108.7011.27.2
Nov18° / 10°1118.8010.46.1
Dec13° / 908.70.29.93.7

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 21% of December, with mostly cloudy or overcast conditions the remaining 47%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15743
25644
35644
45545
55545
65446
75446
85347
95347
105347
115248
125248
135248
145149
155149
165149
175149
185149
195248
205248
215248
225248
235248
245248
255347
265347
275347
285248
295248
305248
315149

Chance of precipitation in December

Any precipitationSnow

Isa gets around 90 mm of rain and snow over 8.7 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 31% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
1310
2310
3310
4310
5310
6300
7300
8300
9290
10290
11290
12280
13280
14280
15271
16271
17271
18271
19261
20261
21261
22261
23261
24261
25261
26261
27271
28272
29272
30272
31272

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 97% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)
19262
29262
39262
49451
59451
69451
79541
89541
99541
109730
119730
129730
139730
149730
159730
169730
179820
189820
199820
209820
219820
229820
239820
249910
259910
269910
279910
289910
299910
309910
319910

Wind in December

Winds average 10 km/h in December.

Across December, daily wind ranges from about 9 km/h on the calmest days to 10 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
19calm
29calm
310calm
410calm
510calm
610calm
710calm
810calm
910calm
1010calm
1110calm
1210calm
1310calm
1410calm
1510calm
1610calm
1710calm
1810calm
1910calm
2010calm
2110calm
2210calm
2310calm
2410calm
2510calm
2610calm
2710calm
2810calm
2910calm
3010calm
3110calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 10 h 06 min at the start of December to 9 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:06 AM to 7:23 AM, and sunset from 5:09 PM to 5:19 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
110.17:065:09
210.07:075:09
310.07:075:09
410.07:085:09
510.07:095:09
610.07:105:09
710.07:105:09
810.07:115:09
910.07:125:09
109.97:135:09
119.97:135:10
129.97:145:10
139.97:155:10
149.97:155:10
159.97:165:11
169.97:165:11
179.97:175:11
189.97:185:12
199.97:185:12
209.97:195:13
219.97:195:13
229.97:205:13
239.97:205:14
249.97:205:14
259.97:215:15
269.97:215:16
279.97:225:16
289.97:225:17
299.97:225:17
309.97:235:18
319.97:235:19

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.42 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.42 kWh/m² to a high of 5.06 kWh/m² in May across the year — December's 2.42 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
12.5Moderate
22.5Moderate
32.5Moderate
42.5Moderate
52.5Moderate
62.4Moderate
72.4Moderate
82.4Moderate
92.4Moderate
102.4Moderate
112.4Moderate
122.4Moderate
132.4Moderate
142.4Moderate
152.4Moderate
162.4Moderate
172.4Moderate
182.4Moderate
192.4Moderate
202.4Moderate
212.4Moderate
222.4Moderate
232.5Moderate
242.5Moderate
252.5Moderate
262.5Moderate
272.5Moderate
282.5Moderate
292.5Moderate
302.5Moderate
312.5Moderate
Planning a trip in December

Hazard calendar for Isa

In seasonPeak

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

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

Isa's rainy season runs June–July, 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 Isa?

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

3.7
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 Isa.

What to pack for Isa in December

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

In December, Isa sees daytime highs around 13°C and nights near 5°C. Worth packing: a warm layer and rain gear. About 9 days see rain.

a warm layerrain gear

Sea temperature near Isa in December

The nearest coast averages about 19°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 23 km away) is warmest in August at about 28°C and coldest in February near 16°C.

It's comfortable for a long swim from May 16 to Dec 4 — about 6.7 months when the water holds above 20°C.

15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan17Cool
Feb16Cool
Mar17Cool
Apr18Cool
May20Refreshing
Jun23Refreshing
Jul26Warm
Aug28Warm
Sep27Warm
Oct24Warm
Nov22Refreshing
Dec19Cool

UV index in Isa in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 3 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Isa peaks around June 22 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJun 22UV 11Dec 23UV 3
UV index (midday)Level
Jan3Moderate
Feb5Moderate
Mar7High
Apr8Very high
May8Very high
Jun11Extreme
Jul11Extreme
Aug9Very high
Sep10Very high
Oct6High
Nov5Moderate
Dec3Moderate

Air quality in Isa 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 Isa is worst in March — around 24 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (July, 13 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateMar 2424 µg/m³Jul 2114 µg/m³
PM2.5 (µg/m³)Level
Jan17Moderate
Feb20Moderate
Mar24Moderate
Apr24Moderate
May22Moderate
Jun18Moderate
Jul13Moderate
Aug14Moderate
Sep14Moderate
Oct14Moderate
Nov16Moderate
Dec15Moderate
Location & terrain

Where is Isa?

Isa sits at 32.1°N, 130.6°E, 183 m above sea level, in Japan. The nearest listed city is Ōkuchi-shinohara, 1.0 km away.

Topography around Isa

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

Within 3 km, the terrain around Isa has significant variations in elevation — a maximum elevation change of 275 m around an average of 207 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 962 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,715 m.

The land around Isa is covered by trees (44%) and cropland (38%) within 3 km, trees (87%) within 16 km, and trees (60%) and water (30%) within 80 km.

3 km
275 m
16 km
962 m
80 km
1,715 m
treesgrasslandcroplandartificial surfaceswater
December weather nearby: Ōkuchi-shinohara 1.0 km · Tsuruda 18 km · Hitoyoshi 21 km · Ebino 22 km · Izumi 23 km · Minamata 26 km · Sashiki 28 km · Aira 33 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 Isa (32.0672°, 130.6118°, elevation 183 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).