Rumoi weather in January

In January, Rumoi sees average daytime highs of -3°C and overnight lows near -9°C, with 67 mm of precipitation across 17.3 wet days and about 9.1 hours of daylight. It is the 12th-warmest and 9th-wettest month of the year here.

Day-to-day highs hold fairly steady near -3°C through the month. The sky is clear or mostly clear about 4% of the time in January, and the air most often feels dry.

Daylight stretches from about 8 h 48 min at the start of January to 9 h 36 min by month's end. Set against the rest of the year, January is Rumoi's 12th-clearest and 7th-windiest month. For the whole year in context, see Rumoi's year-round climate.

Daytime high
-3°
12th warmest
Overnight low
-9°
1st coldest
Precipitation
67 mm
17.3 wet days
Daylight
9 h 06 min
7:11 AM – 4:14 PM
Cloud cover
76%
12th clearest
Wind
12 km/h
7th windiest
Solar energy
1.85 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 January

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near -3°C through the month.

A typical January day in Rumoi reaches about -3°C in the afternoon and slips back to -9°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between -7°C and 1°C. Set against its neighbours, January runs about 3°C cooler than December and about 1°C cooler than February.

-15°-10°-5°151015202531
Avg high (°C)Avg low (°C)
1-2-7
2-2-8
3-2-8
4-2-8
5-2-8
6-3-8
7-3-8
8-3-8
9-3-8
10-3-9
11-3-9
12-3-9
13-3-9
14-3-9
15-3-9
16-3-9
17-3-9
18-3-9
19-3-9
20-3-9
21-3-9
22-3-9
23-3-9
24-3-9
25-3-9
26-3-9
27-3-9
28-3-9
29-3-9
30-3-9
31-3-9

How January really feels in Rumoi

Once humidity and wind are folded in, January 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
31 feel bitter (≤ -10°C)

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

Rumoi weather by month

How January compares with the rest of the year at a glance. January is the 12th-warmest and 9th-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 January

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 4% of the time in January, the cloudiest month of the year.

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

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
12179
22179
32179
42179
52179
62179
72179
82179
92179
102179
112278
122278
132278
142278
152278
162278
172278
182278
192179
202179
212179
222080
232080
241981
251882
261882
271783
281783
291783
301684
311684

Chance of precipitation in January

Any precipitationSnow

Rumoi gets around 67 mm of rain and snow over 17.3 wet days in January. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 56% and peaks near 63% on the wettest days, and about 21 days bring snow. The odds ease toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)Snow chance (%)
16372
26372
36272
46272
56171
66071
76070
85970
95870
105869
115769
125769
135768
145668
155668
165667
175567
185567
195466
205466
215466
225466
235466
245466
255466
265366
275366
285366
295266
305266
315266

Humidity in January

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, January 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 January

Winds average 12 km/h in January.

Across January, daily wind ranges from about 12 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
812light breeze
912light breeze
1012light breeze
1112light breeze
1212light breeze
1312light breeze
1412light breeze
1512light breeze
1612calm
1712calm
1812calm
1912calm
2012calm
2112calm
2212calm
2312calm
2412calm
2512light breeze
2612light breeze
2712light breeze
2812light breeze
2912light breeze
3012light breeze
3112light breeze

Sunrise & sunset in January

DaylightNight

Daylight runs from about 8 h 48 min at the start of January to 9 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 48 minutes over January. Sunrise moves from 7:14 AM to 7:00 AM, and sunset from 4:00 PM to 4:33 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
18.87:144:00
28.87:144:00
38.87:144:01
48.87:144:02
58.87:144:03
68.87:144:04
78.97:144:05
88.97:134:06
98.97:134:07
108.97:134:08
118.97:134:09
129.07:134:10
139.07:124:11
149.07:124:12
159.07:114:13
169.17:114:14
179.17:114:16
189.17:104:17
199.17:094:18
209.27:094:19
219.27:084:20
229.27:084:22
239.37:074:23
249.37:064:24
259.37:054:25
269.47:054:27
279.47:044:28
289.47:034:29
299.57:024:31
309.57:014:32
319.67:004:33

Solar energy in January

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in January, about 1.85 kWh/m².

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 — January's 1.85 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
11.6Dim
21.6Dim
31.6Dim
41.6Dim
51.6Dim
61.7Dim
71.7Dim
81.7Dim
91.7Dim
101.7Dim
111.7Dim
121.7Dim
131.8Dim
141.8Dim
151.8Dim
161.8Dim
171.8Dim
181.9Dim
191.9Dim
201.9Dim
211.9Dim
222.0Dim
232.0Dim
242.0Moderate
252.0Moderate
262.1Moderate
272.1Moderate
282.1Moderate
292.2Moderate
302.2Moderate
312.2Moderate
Planning a trip in January

Hazard calendar for Rumoi

In seasonPeak

In January, 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 January a good time to visit Rumoi?

Our two travel scores rate January 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

January is a weaker month for outdoor sightseeing in Rumoi.

What to pack for Rumoi in January

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

In January, Rumoi sees daytime highs around -3°C and nights near -9°C. Pack a warm layer, a heavy coat and rain gear. About 17 days see rain.

a warm layera heavy coatrain gear

Sea temperature near Rumoi in January

The nearest coast averages about 6°C in January — 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 January

LowModerateHighVery highExtreme

Clear-sky midday UV in January 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 January

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where January 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
January 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).