Karuizawa weather in April

In April, Karuizawa sees average daytime highs of 14°C and overnight lows near 5°C, with 122 mm of precipitation across 13.8 wet days and about 12.9 hours of daylight. It is the 7th-warmest and 7th-wettest month of the year here.

Highs climb over the month, from about 12°C in the first days to 17°C by the end. The sky is clear or mostly clear about 32% of the time in April, and the air most often feels dry.

Daylight stretches from about 12 h 18 min at the start of April to 13 h 24 min by month's end. Set against the rest of the year, April is Karuizawa's 6th-clearest and 5th-windiest month. For the whole year in context, see Karuizawa's year-round climate.

Daytime high
14°
7th warmest
Overnight low
6th coldest
Precipitation
122 mm
13.8 wet days
Daylight
12 h 54 min
5:18 AM – 6:13 PM
Cloud cover
60%
6th clearest
Wind
7 km/h
5th windiest
Solar energy
5.3 kWh/m²
Travel score
3.7
out of 10

Temperature in April

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 12°C in the first days to 17°C by the end.

A typical April day in Karuizawa reaches about 14°C in the afternoon and slips back to 5°C overnight — a 10°C spread between the day's warmth and the night's chill. On most days the high lands between 8°C and 20°C. Set against its neighbours, April runs about 6°C warmer than March and about 5°C cooler than May.

10°20°151015202530
Avg high (°C)Avg low (°C)
1111
2112
3122
4122
5122
6123
7123
8133
9133
10133
11134
12144
13144
14144
15144
16145
17145
18155
19155
20155
21156
22156
23166
24166
25166
26167
27167
28177
29177
30177

How April really feels in Karuizawa

Once humidity and wind are folded in, April averages 0 days that feel above 32°C and 4 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
4
wind chill below the day's low

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

Karuizawa weather by month

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

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 32% of the time in April.

Beyond those clear spells, partly cloudy skies cover about 15% of April, with mostly cloudy or overcast conditions the remaining 53%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15050
24951
34951
45050
54951
64951
74951
84852
94852
104852
114852
124753
134753
144654
154654
164654
174753
184753
194654
204654
214654
224654
234654
244654
254654
264654
274654
284555
294555
304456

Chance of precipitation in April

Any precipitationSnow

Karuizawa gets around 122 mm of rain and snow over 13.8 wet days in April. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 46% and peaks near 49% on the wettest days, and about 2 days bring snow.

0%20%40%60%151015202530
Rain chance (%)Snow chance (%)
14315
24314
34313
44313
54312
64411
74411
84510
94510
10469
11469
12479
13478
14488
15498
16497
17497
18497
19496
20496
21495
22485
23484
24484
25473
26473
27472
28472
29461
30461

Humidity in April

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, April 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%151015202530
Dry (%)Comfortable (%)
11000
21000
31000
41000
51000
61000
71000
81000
91000
101000
111000
121000
13991
14991
15991
16991
17991
18991
19991
20991
21991
22991
23991
24991
25991
26991
27991
28991
29991
30982

Wind in April

Winds average 7 km/h in April.

Across April, daily wind ranges from about 7 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

Sunrise & sunset in April

DaylightNight

Daylight runs from about 12 h 18 min at the start of April to 13 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 66 minutes over April. Sunrise moves from 5:40 AM to 5:00 AM, and sunset from 6:00 PM to 6:26 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.35:406:00
212.45:386:01
312.45:376:02
412.55:356:03
512.55:346:04
612.55:326:05
712.65:316:06
812.65:296:07
912.75:286:07
1012.75:266:08
1112.75:256:09
1212.85:246:10
1312.85:226:11
1412.85:216:12
1512.95:196:13
1612.95:186:13
1713.05:176:14
1813.05:156:15
1913.05:146:16
2013.15:136:17
2113.15:116:18
2213.15:106:19
2313.25:096:20
2413.25:076:20
2513.35:066:21
2613.35:056:22
2713.35:046:23
2813.45:026:24
2913.45:016:25
3013.45:006:26

Solar energy in April

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in April, about 5.3 kWh/m².

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 — April's 5.3 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
15.1Bright
25.1Bright
35.1Bright
45.1Bright
55.1Bright
65.2Bright
75.2Bright
85.2Bright
95.2Bright
105.2Bright
115.2Bright
125.2Bright
135.2Bright
145.3Bright
155.3Bright
165.3Bright
175.3Bright
185.3Bright
195.3Bright
205.3Bright
215.3Bright
225.3Bright
235.4Bright
245.4Bright
255.4Bright
265.4Bright
275.5Bright
285.5Bright
295.5Bright
305.5Bright
Planning a trip in April

Hazard calendar for Karuizawa

In seasonPeak

None of Karuizawa's seasonal hazards are active in April. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

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 April a good time to visit Karuizawa?

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

3.7
Sightseeing
7th-best month of the year
0.2
Beach & pool
7th-best month of the year

April is a weaker month for outdoor sightseeing in Karuizawa.

What to pack for Karuizawa in April

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

In April, Karuizawa sees daytime highs around 14°C and nights near 5°C. Pack rain gear. Worth having: a warm layer and sun protection. About 14 days see rain.

rain geara warm layersun protection

UV index in Karuizawa in April

LowModerateHighVery highExtreme

Clear-sky midday UV in April 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 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 April

GoodModeratePoorUnhealthyVery unhealthy

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