Karuizawa weather in May

In May, Karuizawa sees average daytime highs of 19°C and overnight lows near 10°C, with 165 mm of precipitation across 16.8 wet days and about 13.9 hours of daylight. It is the 5th-warmest and 6th-wettest month of the year here.

Highs climb over the month, from about 17°C in the first days to 20°C by the end. The sky is clear or mostly clear about 24% 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 Karuizawa's 8th-clearest and 7th-windiest month. For the whole year in context, see Karuizawa's year-round climate.

Daytime high
19°
5th warmest
Overnight low
10°
8th coldest
Precipitation
165 mm
16.8 wet days
Daylight
13 h 54 min
4:44 AM – 6:39 PM
Cloud cover
67%
8th clearest
Wind
6 km/h
7th windiest
Solar energy
5.52 kWh/m²
Travel score
5.1
out of 10

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 17°C in the first days to 20°C by the end.

A typical May day in Karuizawa reaches about 19°C in the afternoon and slips back to 10°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 14°C and 23°C. Set against its neighbours, May runs about 5°C warmer than April and about 3°C cooler than June.

10°15°20°25°151015202531
Avg high (°C)Avg low (°C)
1178
2178
3178
4188
5188
6188
7189
8189
9189
10189
11189
12189
131910
141910
151910
161910
171910
181910
191910
201911
211911
221911
232011
242011
252011
262011
272012
282012
292012
302012
312012

How May really feels in Karuizawa

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.

Karuizawa weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -4°597.46.59.80.0
Feb / -4°608.66.710.60.0
Mar / -1°11013.17.111.71.3
Apr14° / 12213.82.112.93.7
May19° / 10°16516.80.113.95.1
Jun21° / 15°25422.7014.44.3
Jul25° / 19°28224014.24.5
Aug26° / 19°24024.1013.44.5
Sep22° / 16°24120.6012.24.8
Oct17° / 19515.5011.14.7
Nov11° / 728.80.610.13.1
Dec / -1°497.64.49.60.6

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 24% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 13% of May, with mostly cloudy or overcast conditions the remaining 62%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14456
24456
34357
44357
54258
64159
74159
84060
93862
103862
113961
123862
133862
143862
153763
163862
173862
183763
193862
203763
213763
223664
233664
243664
253466
263466
273466
283367
293367
303070
313070

Chance of precipitation in May

Any precipitation

Karuizawa gets around 165 mm of rain and snow over 16.8 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 54% and peaks near 62% on the wettest days, and about 0 day brings snow. The odds climb toward the end of the month.

0%20%40%60%151015202531
Rain chance (%)
147
247
347
448
549
650
750
851
952
1053
1153
1253
1354
1454
1554
1654
1755
1855
1955
2055
2155
2255
2356
2456
2557
2657
2758
2859
2960
3061
3162

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 91% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)
19820
29820
39820
49820
59820
69730
79730
89730
99730
109640
119640
129640
139550
149550
159361
169361
179271
189271
199181
209091
2189101
2289101
2388111
2487121
2586131
2685141
2784151
2882162
2980182
3078202
3177212

Wind in May

Winds average 6 km/h in May.

Across May, daily wind ranges from about 6 km/h on the calmest days to 7 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (km/h)Feels
17calm
27calm
37calm
47calm
57calm
67calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

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 4:59 AM to 4:35 AM, and sunset from 6:27 PM to 6:51 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.54:596:27
213.54:586:27
313.54:576:28
413.64:556:29
513.64:546:30
613.64:536:31
713.74:526:32
813.74:516:33
913.74:506:34
1013.84:496:34
1113.84:486:35
1213.84:476:36
1313.84:466:37
1413.94:466:38
1513.94:456:39
1613.94:446:39
1714.04:436:40
1814.04:426:41
1914.04:426:42
2014.04:416:43
2114.14:406:44
2214.14:406:44
2314.14:396:45
2414.14:386:46
2514.14:386:47
2614.24:376:47
2714.24:376:48
2814.24:366:49
2914.24:366:50
3014.34:356:50
3114.34:356:51

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.52 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 2.51 kWh/m² to a high of 5.52 kWh/m² in May across the year — May's 5.52 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.5Bright
45.5Bright
55.5Bright
65.5Bright
75.5Bright
85.5Bright
95.5Bright
105.5Bright
115.5Bright
125.5Bright
135.5Bright
145.5Bright
155.5Bright
165.5Bright
175.5Bright
185.5Bright
195.6Bright
205.6Bright
215.6Bright
225.6Bright
235.6Bright
245.6Bright
255.6Bright
265.6Bright
275.5Bright
285.5Bright
295.5Bright
305.5Bright
315.5Bright
Planning a trip in May

Hazard calendar for Karuizawa

In seasonPeak

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

Karuizawa's rainy season runs May–October, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is May a good time to visit Karuizawa?

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

5.1
Sightseeing
1st-best month of the year
2.0
Beach & pool
5th-best month of the year

May is a reasonable time to visit Karuizawa for sightseeing.

What to pack for Karuizawa in May

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

In May, Karuizawa sees daytime highs around 19°C and nights near 10°C. Pack rain gear. Worth having: sun protection. About 17 days see rain.

rain gearsun protection

UV index in Karuizawa in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 8 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Karuizawa peaks around July 18 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJul 18UV 10Dec 23UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar6High
Apr7High
May8Very high
Jun9Very high
Jul10Very high
Aug9Very high
Sep9Very high
Oct6High
Nov3Moderate
Dec2Moderate

Air quality in Karuizawa 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 Karuizawa 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 1821 µg/m³Dec 1810 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar19Moderate
Apr21Moderate
May20Moderate
Jun18Moderate
Jul15Moderate
Aug14Moderate
Sep13Moderate
Oct12Moderate
Nov11Good
Dec10Good
Location & terrain

Where is Karuizawa?

Karuizawa sits at 36.4°N, 138.6°E, 952 m above sea level, in Japan. The nearest listed city is Miyota, 11 km away.

Topography around Karuizawa

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

Within 3 km, the terrain around Karuizawa has large variations in elevation — a maximum elevation change of 632 m around an average of 1,004 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 2,316 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,985 m.

The land around Karuizawa is covered by trees (86%) within 3 km, trees (86%) within 16 km, and trees (80%) within 80 km.

3 km
632 m
16 km
2,316 m
80 km
2,985 m
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Miyota 11 km · Komoro 18 km · Saku 20 km · Annaka 24 km · Tōmi 24 km · Tomioka 26 km · Ueda 32 km · Nakanojō 32 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 Karuizawa (36.35°, 138.6333°, elevation 952 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. 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).