Rumoi weather in May

In May, Rumoi sees average daytime highs of 14°C and overnight lows near 7°C, with 78 mm of precipitation across 11.7 wet days and about 14.5 hours of daylight. It is the 6th-warmest and 7th-wettest month of the year here.

Highs climb over the month, from about 12°C in the first days to 16°C by the end. The sky is clear or mostly clear about 29% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 54 min at the start of May to 15 hours by month's end. Set against the rest of the year, May is Rumoi's 3rd-clearest and 8th-windiest month. For the whole year in context, see Rumoi's year-round climate.

Daytime high
14°
6th warmest
Overnight low
7th coldest
Precipitation
78 mm
11.7 wet days
Daylight
14 h 30 min
4:13 AM – 6:46 PM
Cloud cover
63%
3rd clearest
Wind
11 km/h
8th windiest
Solar energy
5.5 kWh/m²
Travel score
3.8
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 May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 12°C in the first days to 16°C by the end.

A typical May day in Rumoi reaches about 14°C in the afternoon and slips back to 7°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 10°C and 18°C. Set against its neighbours, May runs about 5°C warmer than April and about 4°C cooler than June.

10°15°20°151015202531
Avg high (°C)Avg low (°C)
1125
2125
3125
4125
5125
6126
7126
8136
9136
10136
11137
12137
13137
14147
15147
16147
17147
18148
19148
20148
21158
22158
23158
24159
25159
26159
27159
28169
29169
301610
311610

How May really feels in Rumoi

Once humidity and wind are folded in, May 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

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

Rumoi weather by month

How May compares with the rest of the year at a glance. May is the 6th-warmest and 7th-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 May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 29% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 14% of May, with mostly cloudy or overcast conditions the remaining 57%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14456
24357
34258
44258
54357
64258
74258
84258
94258
104258
114357
124357
134357
144357
154357
164357
174357
184357
194357
204357
214357
224357
234357
244357
254357
264357
274357
284357
294258
304159
314159

Chance of precipitation in May

Any precipitationSnow

Rumoi gets around 78 mm of rain and snow over 11.7 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 38% and peaks near 42% on the wettest days, and about 0 day brings snow. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202531
Rain chance (%)Snow chance (%)
1425
2425
3424
4424
5423
6413
7413
8412
9412
10402
11402
12391
13391
14381
15371
16371
17361
18360
19360
20350
21350
22350
23350
24350
25350
26350
27350
28350
29350
30350
31360

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May 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 (%)
11000
21000
31000
41000
51000
61000
71000
81000
91000
101000
111000
121000
131000
141000
151000
161000
171000
181000
191000
201000
21991
22991
23991
24991
25991
26991
27982
28982
29973
30973
31964

Wind in May

Winds average 11 km/h in May.

Across May, daily wind ranges from about 10 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
112light breeze
212light breeze
312calm
412calm
512calm
612calm
712calm
812calm
911calm
1011calm
1111calm
1211calm
1311calm
1411calm
1511calm
1611calm
1711calm
1811calm
1911calm
2011calm
2111calm
2210calm
2310calm
2410calm
2510calm
2610calm
2710calm
2810calm
2910calm
3010calm
3110calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 54 min at the start of May to 15 hours by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 66 minutes over May. Sunrise moves from 4:33 AM to 4:01 AM, and sunset from 6:28 PM to 7:01 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.94:336:28
214.04:316:30
314.04:306:31
414.14:296:32
514.14:276:33
614.14:266:34
714.24:246:36
814.24:236:37
914.34:226:38
1014.34:216:39
1114.34:196:40
1214.44:186:41
1314.44:176:43
1414.54:166:44
1514.54:156:45
1614.54:136:46
1714.64:126:47
1814.64:116:48
1914.64:106:49
2014.74:096:50
2114.74:086:51
2214.74:076:52
2314.84:076:53
2414.84:066:54
2514.84:056:55
2614.94:046:56
2714.94:036:57
2814.94:036:58
2915.04:026:59
3015.04:017:00
3115.04:017:01

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.5 kWh/m² — the sunniest month for solar.

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 — May's 5.5 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.4Bright
45.4Bright
55.4Bright
65.4Bright
75.4Bright
85.4Bright
95.4Bright
105.4Bright
115.4Bright
125.4Bright
135.4Bright
145.5Bright
155.5Bright
165.5Bright
175.5Bright
185.5Bright
195.5Bright
205.5Bright
215.5Bright
225.6Bright
235.6Bright
245.6Bright
255.6Bright
265.6Bright
275.6Bright
285.6Bright
295.7Bright
305.7Bright
315.7Bright
Planning a trip in May

Hazard calendar for Rumoi

In seasonPeak

In May, 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 May a good time to visit Rumoi?

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

3.8
Sightseeing
5th-best month of the year
0.1
Beach & pool
6th-best month of the year

May is a weaker month for outdoor sightseeing in Rumoi.

What to pack for Rumoi in May

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

In May, Rumoi sees daytime highs around 14°C and nights near 7°C. Worth packing: a warm layer, rain gear and sun protection. About 12 days see rain.

a warm layerrain gearsun protection

Sea temperature near Rumoi in May

The nearest coast averages about 10°C in May — 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 May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 7 — enough to warrant sun protection. 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 May

GoodModeratePoorUnhealthyVery unhealthy

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