Saikai weather in April

In April, Saikai sees average daytime highs of 17°C and overnight lows near 13°C, with 158 mm of rain across 10.7 wet days and about 12.8 hours of daylight. It is the 8th-warmest and 6th-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 34% 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 18 min by month's end. Set against the rest of the year, April is Saikai's 5th-clearest and 7th-windiest month. For the whole year in context, see Saikai's year-round climate.

Daytime high
17°
8th warmest
Overnight low
13°
5th coldest
Rainfall
158 mm
10.7 wet days
Daylight
12 h 48 min
5:57 AM – 6:46 PM
Cloud cover
59%
5th clearest
Wind
14 km/h
7th windiest
Solar energy
5.08 kWh/m²
Travel score
5.3
out of 10

Temperature in April

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 April day in Saikai reaches about 17°C in the afternoon and slips back to 13°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 14°C and 19°C. Set against its neighbours, April runs about 4°C warmer than March and about 4°C cooler than May.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
11511
21511
31512
41512
51612
61612
71612
81612
91612
101612
111613
121713
131713
141713
151713
161713
171713
181714
191714
201814
211814
221814
231814
241814
251815
261815
271815
281915
291915
301915

How April really feels in Saikai

Once humidity and wind are folded in, April 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

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

Saikai weather by month

How April compares with the rest of the year at a glance. April is the 8th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan10° / 709.60.510.12.1
Feb10° / 8590.410.82.4
Mar13° / 13411.1011.73.6
Apr17° / 13°15810.7012.85.3
May21° / 17°17710.4013.76.3
Jun24° / 21°37215.8014.15.7
Jul27° / 25°30616.20145.3
Aug29° / 26°18214.1013.25.2
Sep26° / 23°18811.3012.26.5
Oct22° / 19°1096.7011.27.4
Nov17° / 14°988010.35.8
Dec12° / 819.209.93.3

Cloud cover in April

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 34% of the time in April.

Beyond those clear spells, partly cloudy skies cover about 11% of April, with mostly cloudy or overcast conditions the remaining 55%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14753
24753
34654
44555
54555
64555
74555
84456
94456
104456
114357
124357
134357
144357
154456
164555
174555
184555
194654
204654
214654
224753
234654
244654
254654
264654
274555
284654
294654
304555

Chance of precipitation in April

Any precipitation

Saikai gets around 158 mm of rain over 10.7 wet days in April. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 36% and peaks near 37% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
135
235
334
434
534
634
734
834
934
1035
1135
1235
1336
1436
1537
1637
1737
1837
1937
2037
2137
2237
2337
2437
2537
2637
2736
2836
2936
3035

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 68% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
1861220
2861220
3851320
4841420
5821530
6811630
7801730
8791830
9771940
10762040
11752140
12742240
13722350
14712450
15712450
16692560
17682660
18682660
19662770
20632881
21622981
22612991
235930101
245731111
255532121
265233141
275033152
284834162
294634172
304435193

Wind in April

Winds average 14 km/h in April.

Across April, daily wind ranges from about 14 km/h on the calmest days to 15 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
115light breeze
215light breeze
315light breeze
415light breeze
515light breeze
615light breeze
715light breeze
815light breeze
915light breeze
1015light breeze
1115light breeze
1215light breeze
1315light breeze
1415light breeze
1515light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze

Sunrise & sunset in April

DaylightNight

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

Days grow by about 60 minutes over April. Sunrise moves from 6:17 AM to 5:41 AM, and sunset from 6:35 PM to 6:56 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.36:176:35
212.36:156:36
312.46:146:37
412.46:136:37
512.46:116:38
612.56:106:39
712.56:096:39
812.56:076:40
912.66:066:41
1012.66:056:42
1112.66:036:42
1212.76:026:43
1312.76:016:44
1412.76:006:44
1512.85:586:45
1612.85:576:46
1712.85:566:47
1812.95:556:47
1912.95:536:48
2012.95:526:49
2113.05:516:50
2213.05:506:50
2313.05:496:51
2413.15:476:52
2513.15:466:53
2613.15:456:53
2713.25:446:54
2813.25:436:55
2913.25:426:56
3013.35:416:56

Solar energy in April

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in April, about 5.08 kWh/m².

For context, solar energy here swings from a low near 2.14 kWh/m² to a high of 5.41 kWh/m² in May across the year — April's 5.08 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
14.7Bright
24.8Bright
34.8Bright
44.8Bright
54.8Bright
64.9Bright
74.9Bright
84.9Bright
94.9Bright
105.0Bright
115.0Bright
125.0Bright
135.0Bright
145.0Bright
155.0Bright
165.1Bright
175.1Bright
185.1Bright
195.1Bright
205.1Bright
215.2Bright
225.2Bright
235.2Bright
245.2Bright
255.2Bright
265.2Bright
275.2Bright
285.3Bright
295.3Bright
305.3Bright
Planning a trip in April

Hazard calendar for Saikai

In seasonPeak

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

Saikai sits in the Pacific typhoon belt; the season peaks July–October.

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

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

Is April a good time to visit Saikai?

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

5.3
Sightseeing
6th-best month of the year
1.3
Beach & pool
8th-best month of the year

April is a reasonable time to visit Saikai for sightseeing.

What to pack for Saikai in April

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

In April, Saikai sees daytime highs around 17°C and nights near 13°C. Worth packing: a warm layer, rain gear and sun protection. About 11 days see rain.

a warm layerrain gearsun protection

Sea temperature near Saikai in April

The nearest coast averages about 17°C in April — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 13 km away) is warmest in August at about 27°C and coldest in February near 15°C.

It's comfortable for a long swim from May 27 to Nov 29 — about 6.1 months when the water holds above 20°C.

15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan16Cool
Feb15Cool
Mar16Cool
Apr17Cool
May19Cool
Jun22Refreshing
Jul25Warm
Aug27Warm
Sep26Warm
Oct24Refreshing
Nov21Refreshing
Dec19Cool

UV index in Saikai 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 Saikai peaks around July 15 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highVery highModerateJul 15UV 10Dec 21UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar6High
Apr7Very high
May8Very high
Jun9Very high
Jul10Extreme
Aug8Very high
Sep9Very high
Oct7High
Nov4Moderate
Dec3Moderate

Air quality in Saikai 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 Saikai is worst in April — around 24 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (October, 11 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateModerateGoodModerateApr 1324 µg/m³Oct 1212 µg/m³
PM2.5 (µg/m³)Level
Jan16Moderate
Feb19Moderate
Mar23Moderate
Apr24Moderate
May21Moderate
Jun17Moderate
Jul12Good
Aug12Moderate
Sep12Good
Oct11Good
Nov14Moderate
Dec13Moderate
Location & terrain

Where is Saikai?

Saikai sits at 33.0°N, 129.7°E, 184 m above sea level, in Japan. The nearest listed city is Sasebo, 21 km away.

Topography around Saikai

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

Within 3 km, the terrain around Saikai has significant variations in elevation — a maximum elevation change of 353 m around an average of 182 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 564 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,455 m.

The land around Saikai is covered by trees (96%) within 3 km, water (55%) and trees (42%) within 16 km, and water (68%) and trees (24%) within 80 km.

3 km
353 m
16 km
564 m
80 km
1,455 m
treesgrasslandcroplandartificial surfaceswater
April weather nearby: Sasebo 21 km · Togitsu 23 km · Ōmura 26 km · Obita 27 km · Arita 30 km · Nagasaki 32 km · Ureshinomachi-shimojuku 33 km · Imarichō-kō 37 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 Saikai (32.9839°, 129.6809°, elevation 184 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).