Saku weather in April

In April, Saku sees average daytime highs of 14°C and overnight lows near 4°C, with 102 mm of precipitation across 12.3 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 11°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 Saku's 6th-clearest and 4th-windiest month. For the whole year in context, see Saku's year-round climate.

Daytime high
14°
7th warmest
Overnight low
6th coldest
Precipitation
102 mm
12.3 wet days
Daylight
12 h 54 min
5:19 AM – 6:14 PM
Cloud cover
59%
6th clearest
Wind
7 km/h
4th windiest
Solar energy
5.4 kWh/m²
Travel score
3.9
out of 10

Saku is city in Nagano Prefecture, Japan.

Density
234/km²
people per km²
Founded
2005

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in April

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 11°C in the first days to 17°C by the end.

A typical April day in Saku reaches about 14°C in the afternoon and slips back to 4°C overnight — a 11°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
2111
3111
4121
5122
6122
7122
8132
9132
10133
11133
12143
13143
14143
15144
16144
17154
18154
19154
20155
21155
22165
23165
24165
25166
26166
27176
28176
29176
30177

How April really feels in Saku

Once humidity and wind are folded in, April averages 0 days that feel above 32°C and 7 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
7
wind chill below the day's low

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

Saku 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 / -5°557.57.89.80.0
Feb / -5°5787.110.60.0
Mar / -2°9911.77.311.71.3
Apr14° / 10212.32.312.93.9
May19° / 131150.113.95.4
Jun22° / 14°19719.8014.44.8
Jul26° / 18°22021.6014.24.8
Aug27° / 19°17421.6013.44.8
Sep23° / 15°18717.6012.25.3
Oct17° / 16112.9011.15.0
Nov11° / 647.80.610.13.0
Dec / -2°487.95.39.60.4

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
44951
54852
64852
74852
84753
94753
104753
114753
124753
134852
144753
154753
164654
174654
184654
194555
204555
214654
224654
234654
244654
254555
264654
274555
284654
294654
304654

Chance of precipitation in April

Any precipitationSnow

Saku gets around 102 mm of rain and snow over 12.3 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 41% and peaks near 42% on the wettest days, and about 2 days bring snow.

0%10%20%30%40%50%151015202530
Rain chance (%)Snow chance (%)
14016
24015
34014
44014
54013
64013
74012
84012
94011
104111
114110
124110
13419
14419
15428
16428
17427
18427
19426
20426
21425
22424
23414
24413
25413
26412
27412
28412
29411
30411

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 100% 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
131000
141000
151000
161000
171000
181000
19991
20991
21991
22991
23991
24991
25991
26991
27991
28991
29991
30991

Wind in April

Winds average 7 km/h in April.

Across April, 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.

0246810151015202530
Wind speed (km/h)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
306calm

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 5:01 AM, and sunset from 6:01 PM to 6:26 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.35:406:01
212.45:396:02
312.45:376:03
412.55:366:04
512.55:346:04
612.55:336:05
712.65:326:06
812.65:306:07
912.75:296:08
1012.75:276:09
1112.75:266:10
1212.85:246:10
1312.85:236:11
1412.85:216:12
1512.95:206:13
1612.95:196:14
1713.05:176:15
1813.05:166:16
1913.05:156:16
2013.15:136:17
2113.15:126:18
2213.15:116:19
2313.25:096:20
2413.25:086:21
2513.25:076:22
2613.35:066:23
2713.35:046:23
2813.45:036:24
2913.45:026:25
3013.45:016:26

Solar energy in April

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in April, about 5.4 kWh/m².

For context, solar energy here swings from a low near 2.52 kWh/m² to a high of 5.67 kWh/m² in May across the year — April's 5.4 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
15.1Bright
25.2Bright
35.2Bright
45.2Bright
55.2Bright
65.2Bright
75.3Bright
85.3Bright
95.3Bright
105.3Bright
115.3Bright
125.3Bright
135.3Bright
145.3Bright
155.4Bright
165.4Bright
175.4Bright
185.4Bright
195.4Bright
205.4Bright
215.5Bright
225.5Bright
235.5Bright
245.5Bright
255.5Bright
265.5Bright
275.6Bright
285.6Bright
295.6Bright
305.6Bright
Planning a trip in April

Hazard calendar for Saku

In seasonPeak

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

Saku's rainy season runs April–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 Saku?

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

3.9
Sightseeing
7th-best month of the year
0.3
Beach & pool
7th-best month of the year

April is a weaker month for outdoor sightseeing in Saku.

What to pack for Saku in April

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

In April, Saku sees daytime highs around 14°C and nights near 4°C. Worth packing: a warm layer, rain gear and sun protection. About 12 days see rain.

a warm layerrain gearsun protection

UV index in Saku 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 Saku peaks around July 18 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 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 22UV 2
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5High
Apr7Very high
May9Very high
Jun10Very high
Jul10Very high
Aug10Very high
Sep9Very high
Oct6High
Nov3Moderate
Dec2Moderate

Air quality in Saku 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 Saku 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 Saku?

Saku sits at 36.2°N, 138.5°E, 684 m above sea level, in Japan. The nearest listed city is Komoro, 12 km away.

Topography around Saku

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

Within 3 km, the terrain around Saku has significant variations in elevation — a maximum elevation change of 321 m around an average of 712 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,343 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,145 m.

The land around Saku is covered by cropland (35%), artificial surfaces (32%) and trees (23%) within 3 km, trees (72%) within 16 km, and trees (81%) within 80 km.

3 km
321 m
16 km
1,343 m
80 km
3,145 m
treesgrasslandcroplandartificial surfacesbare terrainwater
April weather nearby: Komoro 12 km · Miyota 14 km · Tōmi 19 km · Karuizawa 20 km · Kamimaruko 22 km · Ueda 27 km · Tomioka 37 km · Chino 39 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 Saku (36.2167°, 138.4833°, elevation 684 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).