Climate and average weather in Yakushima
In Yakushima, the summers are oppressive, hot, showery, and partly cloudy and the winters are cool, windy, and partly cloudy.
Over the course of the year, the temperature in Yakushima typically varies from 12°C to 28°C, and is rarely below 8°C or above 29°C. August is the hottest month of the year, while January is the coldest.
Based on the travel score, the best times of year to visit Yakushima for warm-weather activities are from late March to early June and mid August to early December.
- Hottest
- Aug
- 28°
- Coldest
- Jan
- 12°
- Wettest
- Jun
- 438 mm
- Driest
- Dec
- 114 mm
- Rain / yr
- 2252 mm
- 166 wet days
- Daylight
- 10.0–14.0 h
- shortest–longest
- Elevation
- 0 m
- 30.4°N
- Clearest
- Oct
- 51% cloud
Yakushima is human settlement in Japan.
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Yakushima weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around mid August to early December.
Temperature through the year
Daily average highs and lows in Yakushima, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 3.9 months, from June 14 to October 10, with daily high temperatures above 25°C. The hottest month of the year in Yakushima is August, with an average high of 28°C and low of 27°C.
The cool season lasts 3.1 months, from December 13 to March 15, with daily high temperatures below 17°C. The coldest month of the year in Yakushima is January, with an average low of 12°C and high of 14°C.
Days typically run about 2°C warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 14 | 15 | 17 | 19 | 22 | 25 | 27 | 28 | 27 | 24 | 20 | 16 |
| Avg low (°C) | 12 | 12 | 14 | 17 | 20 | 23 | 26 | 27 | 25 | 22 | 18 | 14 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 14 | 12 |
| Feb | 15 | 12 |
| Mar | 17 | 14 |
| Apr | 19 | 17 |
| May | 22 | 20 |
| Jun | 25 | 23 |
| Jul | 27 | 26 |
| Aug | 28 | 27 |
| Sep | 27 | 25 |
| Oct | 24 | 22 |
| Nov | 20 | 18 |
| Dec | 16 | 14 |
How hot and cold Yakushima really feels
The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.
On the hottest afternoons, once humidity is folded in, Yakushima feels like about 34°C (around August 8). About 43 days a year carry some heat stress, peaking in August.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°C) | 14 | 15 | 17 | 19 | 22 | 25 | 31 | 33 | 28 | 24 | 20 | 16 |
| Air high (°C) | 14 | 15 | 17 | 19 | 22 | 25 | 27 | 28 | 27 | 24 | 20 | 16 |
| Feels-like low (°C) | 12 | 12 | 14 | 17 | 20 | 23 | 26 | 27 | 25 | 22 | 18 | 14 |
| Air low (°C) | 12 | 12 | 14 | 17 | 20 | 23 | 26 | 27 | 25 | 22 | 18 | 14 |
| Feels-like high (°C) | Air high (°C) | Feels-like low (°C) | Air low (°C) | |
|---|---|---|---|---|
| Jan | 14 | 14 | 12 | 12 |
| Feb | 15 | 15 | 12 | 12 |
| Mar | 17 | 17 | 14 | 14 |
| Apr | 19 | 19 | 17 | 17 |
| May | 22 | 22 | 20 | 20 |
| Jun | 25 | 25 | 23 | 23 |
| Jul | 31 | 27 | 26 | 26 |
| Aug | 33 | 28 | 27 | 27 |
| Sep | 28 | 27 | 25 | 25 |
| Oct | 24 | 24 | 22 | 22 |
| Nov | 20 | 20 | 18 | 18 |
| Dec | 16 | 16 | 14 | 14 |
Average hourly temperature in Yakushima
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on August afternoons, near 28°C, and coldest before dawn in January, near 12°C.
Yakushima weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 14° / 12° | 122 | 13.1 | 10.3 | 3.8 |
| Feb | 15° / 12° | 126 | 12.7 | 10.9 | 4.0 |
| Mar | 17° / 14° | 182 | 14.6 | 11.8 | 4.8 |
| Apr | 19° / 17° | 190 | 12.7 | 12.7 | 5.7 |
| May | 22° / 20° | 210 | 12.9 | 13.5 | 6.1 |
| Jun | 25° / 23° | 438 | 19.6 | 13.9 | 5.1 |
| Jul | 27° / 26° | 173 | 12.6 | 13.8 | 5.9 |
| Aug | 28° / 27° | 141 | 14.7 | 13.1 | 5.4 |
| Sep | 27° / 25° | 237 | 15.8 | 12.2 | 5.7 |
| Oct | 24° / 22° | 170 | 13 | 11.3 | 6.5 |
| Nov | 20° / 18° | 149 | 12 | 10.5 | 6.1 |
| Dec | 16° / 14° | 114 | 11.8 | 10.1 | 4.9 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Yakushima gets about 2252 mm of precipitation a year. On a typical day the chance of rain is very wet, but that rises and falls sharply with the seasons.
The wetter season lasts 1.5 months, from around May 26 to Jul 9, peaking in June at about 69% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Dec 26.
June is the wettest month by volume, with 438 mm over about 20 wet days; December is the driest, with 114 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 42 | 45 | 47 | 43 | 42 | 63 | 43 | 48 | 51 | 43 | 40 | 39 |
| Rain days | 13 | 13 | 15 | 13 | 13 | 20 | 13 | 15 | 16 | 13 | 12 | 12 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 42 | 13 |
| Feb | 45 | 13 |
| Mar | 47 | 15 |
| Apr | 43 | 13 |
| May | 42 | 13 |
| Jun | 63 | 20 |
| Jul | 43 | 13 |
| Aug | 48 | 15 |
| Sep | 51 | 16 |
| Oct | 43 | 13 |
| Nov | 40 | 12 |
| Dec | 39 | 12 |
Monthly rainfall
Over a full year, Yakushima collects about 2252 mm of rain across 166 wet days — roughly 188 mm in an average month.
It doesn’t fall evenly. June is the wettest month with 438 mm, while December is the driest at just 114 mm. The three wettest months alone bring about 39% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 122 | 126 | 182 | 190 | 210 | 438 | 173 | 141 | 237 | 170 | 149 | 114 |
| Rain days | 13 | 13 | 15 | 13 | 13 | 20 | 13 | 15 | 16 | 13 | 12 | 12 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 122 | 13 |
| Feb | 126 | 13 |
| Mar | 182 | 15 |
| Apr | 190 | 13 |
| May | 210 | 13 |
| Jun | 438 | 20 |
| Jul | 173 | 13 |
| Aug | 141 | 15 |
| Sep | 237 | 16 |
| Oct | 170 | 13 |
| Nov | 149 | 12 |
| Dec | 114 | 12 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Yakushima, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.
The clearer part of the year begins around July 17 and lasts for 4.8 months, ending around December 8. The clearest month is October, when the sky is clear, mostly clear, or partly cloudy 56% of the time on average.
The cloudier part of the year begins around April 6 and lasts for 3.4 months, ending around July 16. The cloudiest month is June, when it is overcast or mostly cloudy 80% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 34 | 35 | 40 | 39 | 32 | 20 | 40 | 53 | 52 | 56 | 49 | 41 |
| Cloudier (%) | 66 | 65 | 60 | 61 | 68 | 80 | 60 | 47 | 48 | 44 | 51 | 59 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 34 | 66 |
| Feb | 35 | 65 |
| Mar | 40 | 60 |
| Apr | 39 | 61 |
| May | 32 | 68 |
| Jun | 20 | 80 |
| Jul | 40 | 60 |
| Aug | 53 | 47 |
| Sep | 52 | 48 |
| Oct | 56 | 44 |
| Nov | 49 | 51 |
| Dec | 41 | 59 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around June 17, brings about 14 hours of light; the shortest, around December 16, only 10 hours — a swing of roughly 4 hours.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 10.3 | 10.9 | 11.8 | 12.7 | 13.5 | 13.9 | 13.8 | 13.1 | 12.2 | 11.3 | 10.5 | 10.1 |
| Sunrise (AM) | 7:20 | 7:05 | 6:34 | 5:56 | 5:28 | 5:19 | 5:29 | 5:48 | 6:06 | 6:25 | 6:49 | 7:12 |
| Sunset (PM) | 5:34 | 5:59 | 6:20 | 6:40 | 7:00 | 7:16 | 7:17 | 6:55 | 6:17 | 5:40 | 5:16 | 5:15 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 10.3 | 7:20 | 5:34 |
| Feb | 10.9 | 7:05 | 5:59 |
| Mar | 11.8 | 6:34 | 6:20 |
| Apr | 12.7 | 5:56 | 6:40 |
| May | 13.5 | 5:28 | 7:00 |
| Jun | 13.9 | 5:19 | 7:16 |
| Jul | 13.8 | 5:29 | 7:17 |
| Aug | 13.1 | 5:48 | 6:55 |
| Sep | 12.2 | 6:06 | 6:17 |
| Oct | 11.3 | 6:25 | 5:40 |
| Nov | 10.5 | 6:49 | 5:16 |
| Dec | 10.1 | 7:12 | 5:15 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Yakushima averages about 8 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 3 and 13 days.
The sunnier stretch runs 4.5 months, from around Jul 13 to Nov 26. The sunniest month is October, with roughly 13 sunny days (mixed).
The greyest month is June, down near 4 sunny days — about 69% fewer than the October peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 6 | 6 | 8 | 8 | 7 | 4 | 9 | 12 | 11 | 13 | 9 | 7 |
| Sky | Gloomy | Gloomy | Mixed | Mixed | Gloomy | Gloomy | Mixed | Mixed | Mixed | Mixed | Mixed | Gloomy |
| Sunny days | Sky | |
|---|---|---|
| Jan | 6 | Gloomy |
| Feb | 6 | Gloomy |
| Mar | 8 | Mixed |
| Apr | 8 | Mixed |
| May | 7 | Gloomy |
| Jun | 4 | Gloomy |
| Jul | 9 | Mixed |
| Aug | 12 | Mixed |
| Sep | 11 | Mixed |
| Oct | 13 | Mixed |
| Nov | 9 | Mixed |
| Dec | 7 | Gloomy |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
In Yakushima, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 5.8 months, from around May 6 to October 28. The muggiest month is June, when the air feels humid, muggy or worse about 98% of the time.
The most comfortable stretch runs from around October 29 to May 5, and January is the most comfortable month — the air is dry or comfortable 98% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 93 | 87 | 76 | 47 | 11 | 0 | 0 | 0 | 0 | 10 | 49 | 83 |
| Comfortable (%) | 5 | 10 | 16 | 26 | 22 | 2 | 0 | 0 | 2 | 18 | 24 | 12 |
| Humid (%) | 2 | 4 | 8 | 17 | 32 | 14 | 0 | 0 | 8 | 26 | 18 | 5 |
| Muggy (%) | 0 | 0 | 1 | 9 | 25 | 29 | 2 | 2 | 19 | 26 | 9 | 1 |
| Oppressive (%) | 0 | 0 | 0 | 1 | 9 | 35 | 23 | 22 | 41 | 18 | 2 | 0 |
| Miserable (%) | 0 | 0 | 0 | 0 | 0 | 20 | 75 | 77 | 30 | 2 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|---|---|---|
| Jan | 93 | 5 | 2 | 0 | 0 | 0 |
| Feb | 87 | 10 | 4 | 0 | 0 | 0 |
| Mar | 76 | 16 | 8 | 1 | 0 | 0 |
| Apr | 47 | 26 | 17 | 9 | 1 | 0 |
| May | 11 | 22 | 32 | 25 | 9 | 0 |
| Jun | 0 | 2 | 14 | 29 | 35 | 20 |
| Jul | 0 | 0 | 0 | 2 | 23 | 75 |
| Aug | 0 | 0 | 0 | 2 | 22 | 77 |
| Sep | 0 | 2 | 8 | 19 | 41 | 30 |
| Oct | 10 | 18 | 26 | 26 | 18 | 2 |
| Nov | 49 | 24 | 18 | 9 | 2 | 0 |
| Dec | 83 | 12 | 5 | 1 | 0 | 0 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Across the year, average wind speed in Yakushima is typically breezy, near 26 km/h, and varies moderately with the seasons.
The windier part of the year lasts 5.0 months, from around Nov 12 to Apr 13. The windiest month is January, averaging about 30 km/h (windy).
The calmer part of the year runs from around Apr 14 to Oct 4, with July the calmest month at about 22 km/h.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 30 | 30 | 28 | 26 | 24 | 24 | 22 | 23 | 24 | 27 | 26 | 29 |
| Feels | windy | windy | breezy | breezy | breezy | breezy | breezy | breezy | breezy | breezy | breezy | breezy |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 30 | windy |
| Feb | 30 | windy |
| Mar | 28 | breezy |
| Apr | 26 | breezy |
| May | 24 | breezy |
| Jun | 24 | breezy |
| Jul | 22 | breezy |
| Aug | 23 | breezy |
| Sep | 24 | breezy |
| Oct | 27 | breezy |
| Nov | 26 | breezy |
| Dec | 29 | breezy |
Hazard calendar for Yakushima
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Yakushima sits in the Pacific typhoon belt; the season peaks July–October.
Best time to visit Yakushima
To characterize how pleasant the weather is in Yakushima throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around late August, Yakushima is still near the start of its best-weather window — great conditions with the peak-season crowds not yet at full swing.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 18°C and 28°C. Based on this score, the best times of year to visit Yakushima for general outdoor tourist activities run from late March to early June and again from early July to early December, with a peak score in the third week of October.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 3.9 | 4.0 | 4.8 | 5.7 | 6.0 | 5.1 | 5.8 | 5.5 | 5.8 | 6.5 | 6.1 | 4.9 |
| Rating | fair | fair | fair | good | good | fair | good | fair | good | good | good | fair |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 3.9 | fair |
| Feb | 4.0 | fair |
| Mar | 4.8 | fair |
| Apr | 5.7 | good |
| May | 6.0 | good |
| Jun | 5.1 | fair |
| Jul | 5.8 | good |
| Aug | 5.5 | fair |
| Sep | 5.8 | good |
| Oct | 6.5 | good |
| Nov | 6.1 | good |
| Dec | 4.9 | fair |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best time of year to visit Yakushima for hot-weather activities is from early July to late October, with a peak score in the last week of July.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Yakushima, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
For a warm-season trip around August (highs near 28°C), the essentials are light clothes, rain gear, sun protection and a windbreaker. In the cold season around January (highs near 14°C), pack a warm layer, rain gear and a windbreaker.
In August, Yakushima sees daytime highs around 28°C and nights near 27°C. Pack light clothes and rain gear. Worth having: sun protection and a windbreaker. About 15 days see rain.
Sea temperature near Yakushima
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea offshore is warmest in August at about 29°C and coldest in February near 20°C.
It's comfortable for a long swim from Feb 25 to Feb 7 — about 11.4 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 21 | 20 | 20 | 21 | 23 | 25 | 28 | 29 | 28 | 26 | 24 | 22 |
| Comfort | Refreshing | Cool | Refreshing | Refreshing | Refreshing | Warm | Warm | Tropical | Warm | Warm | Warm | Refreshing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 21 | Refreshing |
| Feb | 20 | Cool |
| Mar | 20 | Refreshing |
| Apr | 21 | Refreshing |
| May | 23 | Refreshing |
| Jun | 25 | Warm |
| Jul | 28 | Warm |
| Aug | 29 | Tropical |
| Sep | 28 | Warm |
| Oct | 26 | Warm |
| Nov | 24 | Warm |
| Dec | 22 | Refreshing |
UV index (midday) in Yakushima by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Yakushima peaks around June 22 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 4 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 4 | 6 | 7 | 9 | 9 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Level | Moderate | High | Very high | Very high | Very high | Extreme | Extreme | Very high | Extreme | High | High | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 4 | Moderate |
| Feb | 6 | High |
| Mar | 7 | Very high |
| Apr | 9 | Very high |
| May | 9 | Very high |
| Jun | 11 | Extreme |
| Jul | 11 | Extreme |
| Aug | 10 | Very high |
| Sep | 10 | Extreme |
| Oct | 7 | High |
| Nov | 5 | High |
| Dec | 4 | Moderate |
Average hourly UV index in Yakushima
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in June the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 6.5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 3.5 | 5 | 6.5 | 7.5 | 8 | 8.5 | 8.5 | 8 | 7.5 | 6 | 4.5 | 3.5 |
| UV ≥ 6 (h/day) | 0 | 0 | 3 | 4.5 | 5 | 6.5 | 6 | 5.5 | 5 | 2.5 | 0 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 3.5 | 0 |
| Feb | 5 | 0 |
| Mar | 6.5 | 3 |
| Apr | 7.5 | 4.5 |
| May | 8 | 5 |
| Jun | 8.5 | 6.5 |
| Jul | 8.5 | 6 |
| Aug | 8 | 5.5 |
| Sep | 7.5 | 5 |
| Oct | 6 | 2.5 |
| Nov | 4.5 | 0 |
| Dec | 3.5 | 0 |
Air quality in Yakushima by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.
Air quality in Yakushima is worst in April — around 21 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (July, 10 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) | 13 | 16 | 20 | 21 | 19 | 13 | 10 | 11 | 10 | 10 | 11 | 10 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 13 | Moderate |
| Feb | 16 | Moderate |
| Mar | 20 | Moderate |
| Apr | 21 | Moderate |
| May | 19 | Moderate |
| Jun | 13 | Moderate |
| Jul | 10 | Good |
| Aug | 11 | Good |
| Sep | 10 | Good |
| Oct | 10 | Good |
| Nov | 11 | Good |
| Dec | 10 | Good |
Growing season
Yakushima is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| Frost nights | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 100 | 0 |
| Feb | 100 | 0 |
| Mar | 100 | 0 |
| Apr | 100 | 0 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 100 | 0 |
| Nov | 100 | 0 |
| Dec | 100 | 0 |
Growing degree days
Growing degree days tally heat above 10°C: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Yakushima banks about 3,743 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around August.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 90 | 92 | 165 | 248 | 350 | 420 | 520 | 540 | 480 | 405 | 277 | 158 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 90 |
| Feb | 92 |
| Mar | 165 |
| Apr | 248 |
| May | 350 |
| Jun | 420 |
| Jul | 520 |
| Aug | 540 |
| Sep | 480 |
| Oct | 405 |
| Nov | 277 |
| Dec | 158 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Yakushima receives about 4.1 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 2.2 and 6.0 kWh/m².
The brighter stretch of the year lasts 6.5 months, from around Mar 20 to Oct 2. The brightest month is July, averaging about 5.8 kWh/m² (bright).
The dimmest month is December, down near 2.3 kWh/m² — roughly 60% less than the July peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 2.4 | 3.1 | 4.0 | 5.0 | 5.3 | 4.5 | 5.9 | 5.7 | 4.6 | 3.7 | 2.7 | 2.2 |
| Level | Moderate | Moderate | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Moderate | Moderate | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 2.4 | Moderate |
| Feb | 3.1 | Moderate |
| Mar | 4.0 | Bright |
| Apr | 5.0 | Bright |
| May | 5.3 | Bright |
| Jun | 4.5 | Bright |
| Jul | 5.9 | Bright |
| Aug | 5.7 | Bright |
| Sep | 4.6 | Bright |
| Oct | 3.7 | Moderate |
| Nov | 2.7 | Moderate |
| Dec | 2.2 | Moderate |
Where is Yakushima?
Yakushima sits at 30.4°N, 130.6°E, 0 m above sea level, in Japan. The nearest listed city is Nishinoomote, 51 km away.
Topography around Yakushima
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Yakushima.
Within 3 km, the terrain around Yakushima has large variations in elevation — a maximum elevation change of 608 m around an average of 81 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,916 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,893 m.
The land around Yakushima is covered by trees (54%) and water (44%) within 3 km, water (67%) and trees (33%) within 16 km, and water (93%) 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 Yakushima (30.388°, 130.6492°, elevation 0 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).