Itoigawa weather in May

In May, Itoigawa sees average daytime highs of 17°C and overnight lows near 12°C, with 139 mm of rain across 14.2 wet days and about 14 hours of daylight. It is the 6th-warmest and 12th-wettest month of the year here.

Highs climb over the month, from about 15°C in the first days to 19°C by the end. The sky is clear or mostly clear about 28% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 30 min at the start of May to 14 h 18 min by month's end. Set against the rest of the year, May is Itoigawa's 2nd-clearest and 8th-windiest month. For the whole year in context, see Itoigawa's year-round climate.

Daytime high
17°
6th warmest
Overnight low
12°
7th coldest
Rainfall
139 mm
14.2 wet days
Daylight
14 hours
4:46 AM – 6:44 PM
Cloud cover
63%
2nd clearest
Wind
8 km/h
8th windiest
Solar energy
5.67 kWh/m²
Travel score
4.9
out of 10

Itoigawa is city in Niigata prefecture, Japan.

Density
55/km²
people per km²
Founded
1954

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 15°C in the first days to 19°C by the end.

A typical May day in Itoigawa reaches about 17°C in the afternoon and slips back to 12°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 13°C and 21°C. Set against its neighbours, May runs about 6°C warmer than April and about 4°C cooler than June.

10°15°20°25°151015202531
Avg high (°C)Avg low (°C)
1159
2159
31510
41510
51510
61610
71610
81611
91611
101611
111611
121611
131711
141712
151712
161712
171712
181712
191712
201712
211813
221813
231813
241813
251813
261813
271814
281914
291914
301914
311914

How May really feels in Itoigawa

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.

Itoigawa weather by month

How May compares with the rest of the year at a glance. May is the 6th-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -0°28826.322.89.70.0
Feb / -1°21921.818.710.60.0
Mar / 20020.512.911.70.4
Apr11° / 14314.82.412.92.6
May17° / 12°13914.20144.9
Jun21° / 17°17314.3014.55.5
Jul25° / 21°25418.8014.35.3
Aug27° / 23°19718.1013.45.3
Sep23° / 19°23518.2012.35.3
Oct18° / 14°21617.30114.7
Nov12° / 21319.12.4102.5
Dec / 27424.315.19.50.4

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 28% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 57%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14357
24456
34456
44555
54456
64456
74456
84456
94357
104357
114357
124357
134357
144357
154456
164456
174456
184456
194357
204357
214258
224258
234357
244456
254357
264258
274258
284258
294258
304159
314060

Chance of precipitation in May

Any precipitation

Itoigawa gets around 139 mm of rain over 14.2 wet days in May, the driest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 45% and peaks near 48% on the wettest days.

0%20%40%60%151015202531
Rain chance (%)
144
244
344
444
544
645
745
846
946
1047
1147
1248
1348
1448
1548
1647
1747
1847
1946
2046
2145
2245
2344
2444
2543
2642
2741
2841
2940
3040
3140

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 84% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)
19730
29730
39640
49640
59550
69550
79460
89460
99370
109370
119181
129181
139091
149091
1589101
1688111
1787121
1886131
1984142
2083152
2182162
2281172
2379192
2476213
2575223
2673243
2771263
2868284
2964315
3061336
3157367

Wind in May

Winds average 8 km/h in May.

Across May, daily wind ranges from about 7 km/h on the calmest days to 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
19calm
29calm
39calm
49calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm
317calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 30 min at the start of May to 14 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 48 minutes over May. Sunrise moves from 5:01 AM to 4:36 AM, and sunset from 6:31 PM to 6:56 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.55:016:31
213.55:006:32
313.64:586:33
413.64:576:34
513.64:566:34
613.74:556:35
713.74:546:36
813.74:536:37
913.84:526:38
1013.84:516:39
1113.84:506:40
1213.94:496:41
1313.94:486:42
1413.94:476:42
1513.94:466:43
1614.04:466:44
1714.04:456:45
1814.04:446:46
1914.14:436:47
2014.14:426:47
2114.14:426:48
2214.14:416:49
2314.24:406:50
2414.24:406:51
2514.24:396:51
2614.24:396:52
2714.24:386:53
2814.34:376:54
2914.34:376:54
3014.34:376:55
3114.34:366:56

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.67 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 1.88 kWh/m² to a high of 5.67 kWh/m² in May across the year — May's 5.67 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.5Bright
45.5Bright
55.6Bright
65.6Bright
75.6Bright
85.6Bright
95.6Bright
105.6Bright
115.6Bright
125.6Bright
135.6Bright
145.6Bright
155.7Bright
165.7Bright
175.7Bright
185.7Bright
195.7Bright
205.8Bright
215.8Bright
225.8Bright
235.8Bright
245.8Bright
255.8Bright
265.8Bright
275.8Bright
285.8Bright
295.8Bright
305.8Bright
315.8Bright
Planning a trip in May

Hazard calendar for Itoigawa

In seasonPeak

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

Itoigawa 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 Itoigawa?

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

4.9
Sightseeing
5th-best month of the year
1.2
Beach & pool
6th-best month of the year

May is a reasonable time to visit Itoigawa for sightseeing.

What to pack for Itoigawa in May

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

In May, Itoigawa sees daytime highs around 17°C and nights near 12°C. Pack rain gear. Worth having: a warm layer and sun protection. About 14 days see rain.

rain geara warm layersun protection

Sea temperature near Itoigawa in May

The nearest coast averages about 15°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 27°C and coldest in March near 10°C.

It's comfortable for a long swim from Jun 20 to Nov 1 — about 4.4 months when the water holds above 20°C.

10°20°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan13Bracing
Feb11Bracing
Mar10Bracing
Apr11Bracing
May15Bracing
Jun20Cool
Jul23Refreshing
Aug27Warm
Sep25Warm
Oct22Refreshing
Nov19Cool
Dec15Cool

UV index in Itoigawa in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Itoigawa peaks around August 12 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateAug 12UV 10Dec 20UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul10Very high
Aug10Very high
Sep9Very high
Oct5High
Nov3Moderate
Dec2Low

Air quality in Itoigawa 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 Itoigawa is worst in April — around 21 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (December, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1721 µg/m³Dec 1510 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar20Moderate
Apr21Moderate
May20Moderate
Jun18Moderate
Jul15Moderate
Aug13Moderate
Sep12Good
Oct11Good
Nov11Good
Dec10Good
Location & terrain

Where is Itoigawa?

Itoigawa sits at 37.0°N, 137.8°E, 15 m above sea level, in Japan. The nearest listed city is Nyūzen, 33 km away.

Topography around Itoigawa

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

Within 3 km, the terrain around Itoigawa has significant variations in elevation — a maximum elevation change of 312 m around an average of 44 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,586 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,069 m.

The land around Itoigawa is covered by trees (35%), water (30%) and artificial surfaces (24%) within 3 km, trees (50%) and water (45%) within 16 km, and trees (49%) and water (40%) within 80 km.

3 km
312 m
16 km
1,586 m
80 km
3,069 m
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Nyūzen 33 km · Arai 34 km · Myoko 36 km · Jōetsu 37 km · Kurobe-shi 38 km · Uozu 48 km · Iiyama 50 km · Nagano 52 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 Itoigawa (37.0333°, 137.85°, elevation 15 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).