Rumoi weather in December

In December, Rumoi sees average daytime highs of -0°C and overnight lows near -5°C, with 102 mm of precipitation across 21.6 wet days and about 8.8 hours of daylight. It is the 10th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 2°C in the first days to -2°C by the end. The sky is clear or mostly clear about 4% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 hours at the start of December to 8 h 48 min by month's end. Set against the rest of the year, December is Rumoi's 11th-clearest and 2nd-windiest month. For the whole year in context, see Rumoi's year-round climate.

Daytime high
-0°
10th warmest
Overnight low
-5°
3rd coldest
Precipitation
102 mm
21.6 wet days
Daylight
8 h 42 min
7:08 AM – 3:51 PM
Cloud cover
75%
11th clearest
Wind
14 km/h
2nd windiest
Solar energy
1.43 kWh/m²
Travel score
0.0
out of 10

Rumoi is city in Hokkaido, Japan.

Density
89/km²
people per km²
Founded
1947

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 2°C in the first days to -2°C by the end.

A typical December day in Rumoi reaches about -0°C in the afternoon and slips back to -5°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between -4°C and 4°C. Set against its neighbours, December runs about 7°C cooler than November and about 3°C warmer than January.

-15°-10°-5°10°151015202531
Avg high (°C)Avg low (°C)
12-2
22-3
32-3
42-3
51-3
61-3
71-4
81-4
91-4
100-4
110-5
120-5
130-5
140-5
150-5
16-1-5
17-1-6
18-1-6
19-1-6
20-1-6
21-1-6
22-1-6
23-1-6
24-1-7
25-1-7
26-2-7
27-2-7
28-2-7
29-2-7
30-2-7
31-2-7

How December really feels in Rumoi

Once humidity and wind are folded in, December averages 0 days that feel above 32°C and 31 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
31
20 feel bitter (≤ -10°C)

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Rumoi weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-3° / -9°6717.3219.10.0
Feb-2° / -8°5514.217.110.20.0
Mar / -5°6613.614.111.60.0
Apr / 6611.94.613.21.5
May14° / 7811.70.314.53.8
Jun18° / 12°7010.4015.25.6
Jul22° / 17°12112.4014.96.2
Aug24° / 18°14313.7013.86.2
Sep20° / 14°13713.9012.35.7
Oct14° / 11515.90.310.83.6
Nov / 12419.411.49.40.7
Dec-0° / -5°10221.622.68.80.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 4% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 16% of December, with mostly cloudy or overcast conditions the remaining 80%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
12278
22278
32179
42179
52080
62080
71981
81981
91981
101981
112080
122080
132080
142080
152080
162080
172080
182080
192080
202080
212080
222080
232080
241981
252080
262080
272080
282179
292179
302179
312179

Chance of precipitation in December

Any precipitationSnow

Rumoi gets around 102 mm of rain and snow over 21.6 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 68% and peaks near 72% on the wettest days, and about 23 days bring snow. The odds ease toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)Snow chance (%)
17164
27165
37267
47268
57269
67270
77271
87271
97272
107273
117173
127173
137073
146974
156974
166873
176873
186773
196773
206773
216673
226673
236673
246673
256573
266573
276473
286473
296472
306372
316372

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 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in December

Winds average 14 km/h in December.

Across December, daily wind ranges from about 13 km/h on the calmest days to 15 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
115light breeze
215light breeze
315light breeze
415light breeze
515light breeze
615light breeze
715light breeze
815light breeze
915light breeze
1015light breeze
1115light breeze
1214light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2513light breeze
2613light breeze
2713light breeze
2813light breeze
2913light breeze
3013light breeze
3113light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 hours at the start of December to 8 h 48 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 6:54 AM to 7:14 AM, and sunset from 3:52 PM to 3:59 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.06:543:52
28.96:563:52
38.96:573:51
48.96:583:51
58.96:593:51
68.97:003:51
78.87:003:51
88.87:013:51
98.87:023:51
108.87:033:51
118.87:043:51
128.87:053:51
138.87:063:51
148.77:063:51
158.77:073:51
168.77:083:51
178.77:083:52
188.77:093:52
198.77:103:52
208.77:103:53
218.77:113:53
228.77:113:54
238.77:123:54
248.77:123:55
258.77:123:55
268.77:133:56
278.77:133:56
288.77:133:57
298.77:143:58
308.77:143:58
318.87:143:59

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.43 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.43 kWh/m² to a high of 5.5 kWh/m² in May across the year — December's 1.43 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.5Dim
21.5Dim
31.4Dim
41.4Dim
51.4Dim
61.4Dim
71.4Dim
81.4Dim
91.4Dim
101.4Dim
111.4Dim
121.4Dim
131.4Dim
141.4Dim
151.4Dim
161.4Dim
171.4Dim
181.4Dim
191.4Dim
201.4Dim
211.4Dim
221.4Dim
231.5Dim
241.5Dim
251.5Dim
261.5Dim
271.5Dim
281.5Dim
291.5Dim
301.6Dim
311.6Dim
Planning a trip in December

Hazard calendar for Rumoi

In seasonPeak

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

Rumoi 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 Rumoi?

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

0.0
Sightseeing
9th-best month of the year
0.0
Beach & pool
7th-best month of the year

December is a weaker month for outdoor sightseeing in Rumoi.

What to pack for Rumoi in December

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

In December, Rumoi sees daytime highs around -0°C and nights near -5°C. Pack a warm layer, a heavy coat and rain gear. About 22 days see rain.

a warm layera heavy coatrain gear

Sea temperature near Rumoi in December

The nearest coast averages about 9°C in December — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 21°C and coldest in February near 5°C.

It's comfortable for a long swim from Aug 3 to Sep 20 — about 1.6 months when the water holds above 20°C.

10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarm
Sea temperature (°C)Comfort
Jan6Bracing
Feb5Bracing
Mar5Bracing
Apr7Bracing
May10Bracing
Jun14Bracing
Jul18Cool
Aug21Refreshing
Sep21Refreshing
Oct17Cool
Nov13Bracing
Dec9Bracing

UV index in Rumoi in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Rumoi peaks around August 15 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighHighVery highHighModerateLowAug 15UV 8Dec 20UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar3Moderate
Apr5High
May7Very high
Jun7High
Jul7High
Aug8Very high
Sep6High
Oct4Moderate
Nov2Low
Dec1Low

Air quality in Rumoi 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 Rumoi is worst in April — around 17 µg/m³ PM2.5 (moderate), about 2.4× the cleanest month (December, 7 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1317 µg/m³Dec 217 µg/m³
PM2.5 (µg/m³)Level
Jan7Good
Feb10Good
Mar16Moderate
Apr17Moderate
May15Moderate
Jun10Good
Jul10Good
Aug8Good
Sep7Good
Oct9Good
Nov9Good
Dec7Good
Location & terrain

Where is Rumoi?

Rumoi sits at 43.9°N, 141.6°E, 35 m above sea level, in Japan. The nearest listed city is Fukagawa, 41 km away.

Topography around Rumoi

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

Within 3 km, the terrain around Rumoi has only modest variations in elevation — a maximum elevation change of 248 m around an average of 40 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 731 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,471 m.

The land around Rumoi is covered by trees (41%) and water (34%) within 3 km, trees (53%) and water (40%) within 16 km, and trees (51%) and water (35%) within 80 km.

3 km
248 m
16 km
731 m
80 km
1,471 m
treesgrasslandcroplandartificial surfaceswater
December weather nearby: Fukagawa 41 km · Takikawa 47 km · Sunagawa 54 km · Asahikawa 61 km · Minamishibetsuchō 63 km · Ashibetsu 64 km · Bibai 70 km · Nayoro 80 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 Rumoi (43.9344°, 141.6428°, elevation 35 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).