Saikai weather in May

In May, Saikai sees average daytime highs of 21°C and overnight lows near 17°C, with 177 mm of rain across 10.4 wet days and about 13.7 hours of daylight. It is the 6th-warmest and 5th-wettest month of the year here.

Highs climb over the month, from about 19°C in the first days to 22°C by the end. The sky is clear or mostly clear about 30% of the time in May, and the air most often feels humid.

Daylight stretches from about 13 h 18 min at the start of May to 14 hours by month's end. Set against the rest of the year, May is Saikai's 8th-clearest and 11th-windiest month. For the whole year in context, see Saikai's year-round climate.

Daytime high
21°
6th warmest
Overnight low
17°
7th coldest
Rainfall
177 mm
10.4 wet days
Daylight
13 h 42 min
5:27 AM – 7:08 PM
Cloud cover
63%
8th clearest
Wind
13 km/h
11th windiest
Solar energy
5.41 kWh/m²
Travel score
6.3
out of 10

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 19°C in the first days to 22°C by the end.

A typical May day in Saikai reaches about 21°C in the afternoon and slips back to 17°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 19°C and 23°C. Set against its neighbours, May runs about 4°C warmer than April and about 3°C cooler than June.

10°15°20°25°151015202531
Avg high (°C)Avg low (°C)
11915
21916
31916
41916
52016
62016
72016
82016
92016
102017
112017
122017
132017
142117
152117
162117
172117
182118
192118
202118
212118
222118
232218
242218
252218
262218
272219
282219
292219
302219
312219

How May really feels in Saikai

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.

Saikai weather by month

How May compares with the rest of the year at a glance. May is the 6th-warmest and 5th-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 May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 30% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 12% of May, with mostly cloudy or overcast conditions the remaining 58%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14555
24555
34357
44357
54357
64258
74159
84258
94258
104159
114159
124159
134159
144159
154258
164357
174258
184258
194159
204357
214258
224258
234258
244357
254357
264258
274357
284258
294258
304060
314159

Chance of precipitation in May

Any precipitation

Saikai gets around 177 mm of rain over 10.4 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 34% and peaks near 36% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
135
235
335
435
536
636
736
836
936
1036
1136
1236
1335
1435
1534
1634
1734
1833
1933
2032
2132
2232
2332
2432
2532
2632
2732
2832
2933
3033
3134

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the humid band about 37% of days. Sticky, muggy-or-worse air turns up on roughly 10% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
142352030
240362130
338372240
436382340
534382440
632392550
730392650
829392750
927402760
1026402860
1125402960
1223403060
1322403270
1421393370
1520393570
1618383670
1717373880
1816364080
1915354280
2014344390
2113334590
22123246100
23113048110
24102949120
2592751130
2682651150
2772551170
2862352190
2962251210
3052051240
3141950261

Wind in May

Winds average 13 km/h in May.

Across May, daily wind ranges from about 11 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
114light breeze
214light breeze
314light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1712light breeze
1812light breeze
1912light breeze
2012light breeze
2112light breeze
2212calm
2312calm
2412calm
2512calm
2612calm
2712calm
2811calm
2911calm
3011calm
3111calm

Sunrise & sunset in May

DaylightNight

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

Days grow by about 42 minutes over May. Sunrise moves from 5:40 AM to 5:19 AM, and sunset from 6:57 PM to 7:19 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.35:406:57
213.35:396:58
313.35:386:59
413.45:376:59
513.45:367:00
613.45:357:01
713.55:347:02
813.55:337:02
913.55:327:03
1013.55:317:04
1113.65:317:05
1213.65:307:05
1313.65:297:06
1413.65:287:07
1513.75:277:08
1613.75:277:08
1713.75:267:09
1813.75:257:10
1913.85:257:11
2013.85:247:11
2113.85:237:12
2213.85:237:13
2313.95:227:13
2413.95:227:14
2513.95:217:15
2613.95:217:15
2713.95:207:16
2813.95:207:17
2914.05:207:17
3014.05:197:18
3114.05:197:19

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.41 kWh/m² — the sunniest month for solar.

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 — May's 5.41 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.3Bright
45.3Bright
55.3Bright
65.3Bright
75.3Bright
85.3Bright
95.3Bright
105.3Bright
115.3Bright
125.3Bright
135.4Bright
145.4Bright
155.4Bright
165.4Bright
175.4Bright
185.4Bright
195.4Bright
205.5Bright
215.5Bright
225.5Bright
235.5Bright
245.5Bright
255.5Bright
265.5Bright
275.5Bright
285.4Bright
295.4Bright
305.4Bright
315.4Bright
Planning a trip in May

Hazard calendar for Saikai

In seasonPeak

In May, Saikai sits inside its pacific typhoon and rainy season 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 May a good time to visit Saikai?

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

6.3
Sightseeing
3rd-best month of the year
3.7
Beach & pool
6th-best month of the year

May is a reasonable time to visit Saikai for sightseeing.

What to pack for Saikai in May

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

In May, Saikai sees daytime highs around 21°C and nights near 17°C. Worth packing: rain gear and sun protection. About 10 days see rain.

rain gearsun protection

Sea temperature near Saikai in May

The nearest coast averages about 19°C in May — 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 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 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 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 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
May 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).