Saikai in Fall
In fall (September, October and November), Saikai sees average daytime highs around 22°C and overnight lows near 18°C, with 394 mm of rain over about 26 wet days across the season. It is the 2nd-warmest season and the 3rd-wettest season.
Over the season highs ease from about 28°C in early September to 15°C by late November. The sky is clear or mostly clear about 43% of the time across fall, and the air most often feels dry.
Fall is Saikai's best season of the year to visit on our travel score. For the whole year in context, see Saikai's year-round climate.
- Avg daytime high
- 22°C
- 2nd-warmest season
- Avg overnight low
- 18°C
- Rainfall
- 394 mm
- 26 wet days
- Avg wind
- 14 km/h
- Travel score
- 6.6
- best season of the year
- Months
- Sep · Oct · Nov
Temperature in Saikai in Fall
Over the season highs ease from about 28°C in early September to 15°C by late November.
A typical fall day in Saikai reaches about 22°C and drops to 18°C overnight. The warmest of the three months is September, the coolest November.
How fall really feels in Saikai
Once humidity and wind are folded in, fall brings about 0 days that feel above 32°C and 0 that feel at or below 0°C.
fall 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 the three fall months (September, October and November) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 10° / 7° | 70 | 9.6 | 0.5 | 10.1 | 2.1 |
| Feb | 10° / 7° | 85 | 9 | 0.4 | 10.8 | 2.4 |
| Mar | 13° / 9° | 134 | 11.1 | 0 | 11.7 | 3.6 |
| Apr | 17° / 13° | 158 | 10.7 | 0 | 12.8 | 5.3 |
| May | 21° / 17° | 177 | 10.4 | 0 | 13.7 | 6.3 |
| Jun | 24° / 21° | 372 | 15.8 | 0 | 14.1 | 5.7 |
| Jul | 27° / 25° | 306 | 16.2 | 0 | 14 | 5.3 |
| Aug | 29° / 26° | 182 | 14.1 | 0 | 13.2 | 5.2 |
| Sep | 26° / 23° | 188 | 11.3 | 0 | 12.2 | 6.5 |
| Oct | 22° / 19° | 109 | 6.7 | 0 | 11.2 | 7.4 |
| Nov | 17° / 14° | 98 | 8 | 0 | 10.3 | 5.8 |
| Dec | 12° / 9° | 81 | 9.2 | 0 | 9.9 | 3.3 |
Cloud cover in Fall
The sky is clear or mostly clear about 43% of the time across fall.
Chance of precipitation in Fall
Saikai gets around 394 mm of rain over 26 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 14 km/h across fall.
Sunrise & sunset in Fall
Daylight runs from about 12 h 42 min in early September to 10 hours by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 3.6 kWh/m².
Hazard calendar for Saikai
In fall, Saikai overlaps 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.
Is fall a good time to visit Saikai?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a reasonable time to visit Saikai for sightseeing.
What to pack for Saikai in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, Saikai sees daytime highs around 22°C and nights near 18°C. Worth packing: light clothes and rain gear. About 26 days see rain.
Sea temperature near Saikai in Fall
The nearest coast averages about 24°C across fall — 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 16 | 15 | 16 | 17 | 19 | 22 | 25 | 27 | 26 | 24 | 21 | 19 |
| Comfort | Cool | Cool | Cool | Cool | Cool | Refreshing | Warm | Warm | Warm | Refreshing | Refreshing | Cool |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 16 | Cool |
| Feb | 15 | Cool |
| Mar | 16 | Cool |
| Apr | 17 | Cool |
| May | 19 | Cool |
| Jun | 22 | Refreshing |
| Jul | 25 | Warm |
| Aug | 27 | Warm |
| Sep | 26 | Warm |
| Oct | 24 | Refreshing |
| Nov | 21 | Refreshing |
| Dec | 19 | Cool |
UV index in Saikai in Fall
Clear-sky midday UV across fall averages 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 3 | 4 | 6 | 7 | 8 | 9 | 10 | 8 | 9 | 7 | 4 | 3 |
| Level | Moderate | Moderate | High | Very high | Very high | Very high | Extreme | Very high | Very high | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 3 | Moderate |
| Feb | 4 | Moderate |
| Mar | 6 | High |
| Apr | 7 | Very high |
| May | 8 | Very high |
| Jun | 9 | Very high |
| Jul | 10 | Extreme |
| Aug | 8 | Very high |
| Sep | 9 | Very high |
| Oct | 7 | High |
| Nov | 4 | Moderate |
| Dec | 3 | Moderate |
Air quality in Saikai in Fall
Average fine-particle pollution (PM2.5) through the year — so you can see where fall 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).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 16 | 19 | 23 | 24 | 21 | 17 | 12 | 12 | 12 | 11 | 14 | 13 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Moderate | Good | Good | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 16 | Moderate |
| Feb | 19 | Moderate |
| Mar | 23 | Moderate |
| Apr | 24 | Moderate |
| May | 21 | Moderate |
| Jun | 17 | Moderate |
| Jul | 12 | Good |
| Aug | 12 | Moderate |
| Sep | 12 | Good |
| Oct | 11 | Good |
| Nov | 14 | Moderate |
| Dec | 13 | Moderate |
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.
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
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.