Iyo in Fall
In fall (September, October and November), Iyo sees average daytime highs around 21°C and overnight lows near 15°C, with 411 mm of rain over about 32 wet days across the season. It is the 2nd-warmest season and the 2nd-wettest season.
Over the season highs ease from about 28°C in early September to 14°C by late November. The sky is clear or mostly clear about 40% of the time across fall, and the air most often feels dry.
Fall is Iyo's best season of the year to visit on our travel score. For the whole year in context, see Iyo's year-round climate.
- Avg daytime high
- 21°C
- 2nd-warmest season
- Avg overnight low
- 15°C
- Rainfall
- 411 mm
- 32 wet days
- Avg wind
- 8 km/h
- Travel score
- 6.0
- best season of the year
- Months
- Sep · Oct · Nov
Temperature in Iyo in Fall
Over the season highs ease from about 28°C in early September to 14°C by late November.
A typical fall day in Iyo reaches about 21°C and drops to 15°C overnight. The warmest of the three months is September, the coolest November.
How fall really feels in Iyo
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.
Iyo 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 | 8° / 2° | 69 | 11.3 | 3.3 | 10 | 1.4 |
| Feb | 9° / 3° | 79 | 10.4 | 2.9 | 10.7 | 1.8 |
| Mar | 13° / 5° | 118 | 12.3 | 0.7 | 11.7 | 3.4 |
| Apr | 18° / 10° | 133 | 11 | 0.1 | 12.8 | 5.5 |
| May | 22° / 15° | 154 | 11.1 | 0 | 13.7 | 6.4 |
| Jun | 25° / 19° | 268 | 15.7 | 0 | 14.2 | 5.6 |
| Jul | 29° / 23° | 239 | 16.8 | 0 | 14 | 4.7 |
| Aug | 30° / 24° | 156 | 15.8 | 0 | 13.3 | 4.5 |
| Sep | 27° / 20° | 187 | 13.6 | 0 | 12.2 | 5.9 |
| Oct | 22° / 15° | 141 | 9.4 | 0 | 11.2 | 6.9 |
| Nov | 16° / 9° | 83 | 9.1 | 0 | 10.2 | 5.3 |
| Dec | 11° / 4° | 83 | 11.4 | 1.9 | 9.8 | 2.6 |
Cloud cover in Fall
The sky is clear or mostly clear about 40% of the time across fall.
Chance of precipitation in Fall
Iyo gets around 411 mm of rain over 32 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 8 km/h across fall.
Sunrise & sunset in Fall
Daylight runs from about 12 h 42 min in early September to 9 h 54 min 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 Iyo
In fall, Iyo overlaps its pacific typhoon season. The full year is below, with each hazard's peak months called out.
Iyo sits in the Pacific typhoon belt; the season peaks July–October.
Is fall a good time to visit Iyo?
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 Iyo for sightseeing.
What to pack for Iyo in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, Iyo sees daytime highs around 21°C and nights near 15°C. Pack rain gear. Worth having: light clothes and a warm layer. About 32 days see rain.
Sea temperature near Iyo in Fall
The nearest coast averages about 23°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 15 km away) is warmest in August at about 26°C and coldest in February near 13°C.
It's comfortable for a long swim from Jun 12 to Nov 17 — about 5.2 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 15 | 13 | 13 | 15 | 17 | 21 | 24 | 26 | 25 | 23 | 20 | 17 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Cool | Refreshing | Warm | Warm | Warm | Refreshing | Refreshing | Cool |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 15 | Bracing |
| Feb | 13 | Bracing |
| Mar | 13 | Bracing |
| Apr | 15 | Bracing |
| May | 17 | Cool |
| Jun | 21 | Refreshing |
| Jul | 24 | Warm |
| Aug | 26 | Warm |
| Sep | 25 | Warm |
| Oct | 23 | Refreshing |
| Nov | 20 | Refreshing |
| Dec | 17 | Cool |
UV index in Iyo 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 Iyo peaks around June 23 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 | 5 | 6 | 7 | 9 | 10 | 10 | 9 | 10 | 7 | 4 | 3 |
| Level | Moderate | Moderate | High | Very high | Very high | Extreme | Extreme | Very high | Very high | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 3 | Moderate |
| Feb | 5 | Moderate |
| Mar | 6 | High |
| Apr | 7 | Very high |
| May | 9 | Very high |
| Jun | 10 | Extreme |
| Jul | 10 | Extreme |
| Aug | 9 | Very high |
| Sep | 10 | Very high |
| Oct | 7 | High |
| Nov | 4 | Moderate |
| Dec | 3 | Moderate |
Air quality in Iyo 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 Iyo is worst in April — around 23 µg/m³ PM2.5 (moderate), about 2.2× 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) | 14 | 17 | 21 | 23 | 21 | 19 | 15 | 15 | 12 | 11 | 12 | 11 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 14 | Moderate |
| Feb | 17 | Moderate |
| Mar | 21 | Moderate |
| Apr | 23 | Moderate |
| May | 21 | Moderate |
| Jun | 19 | Moderate |
| Jul | 15 | Moderate |
| Aug | 15 | Moderate |
| Sep | 12 | Moderate |
| Oct | 11 | Good |
| Nov | 12 | Good |
| Dec | 11 | Good |
Where is Iyo?
Iyo sits at 33.8°N, 132.7°E, 14 m above sea level, in Japan. The nearest listed city is Masaki-chō, 4.0 km away.
Topography around Iyo
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Iyo.
Within 3 km, the terrain around Iyo has significant variations in elevation — a maximum elevation change of 427 m around an average of 50 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 1,141 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,895 m.
The land around Iyo is covered by trees (30%), water (29%) and artificial surfaces (24%) within 3 km, trees (44%) and water (37%) within 16 km, and trees (52%) and water (42%) 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 Iyo (33.7514°, 132.7014°, elevation 14 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.