Climate and average weather in Kokubu-matsuki
In Kokubu-matsuki, the summers are muggy, hot, wet, and partly cloudy and the winters are cool and partly cloudy.
Over the course of the year, the temperature in Kokubu-matsuki typically varies from 3°C to 31°C, and is rarely below -1°C or above 33°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 Kokubu-matsuki for warm-weather activities are from late April to early June and late September to late November.
- Hottest
- Aug
- 31°
- Coldest
- Jan
- 3°
- Wettest
- Jun
- 488 mm
- Driest
- Jan
- 80 mm
- Rain / yr
- 2188 mm
- 151 wet days
- Daylight
- 9.9–14.1 h
- shortest–longest
- Elevation
- 0 m
- 31.7°N
- Clearest
- Oct
- 49% cloud
Kokubu-matsuki is human settlement in Japan.
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Kokubu-matsuki 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 late September to late November.
Temperature through the year
Daily average highs and lows in Kokubu-matsuki, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 3.5 months, from June 19 to October 2, with daily high temperatures above 26°C. The hottest month of the year in Kokubu-matsuki is August, with an average high of 31°C and low of 24°C.
The cool season lasts 3.1 months, from December 5 to March 8, with daily high temperatures below 15°C. The coldest month of the year in Kokubu-matsuki is January, with an average low of 3°C and high of 11°C.
Days typically run about 8°C warmer than nights, with the widest day–night swing (around 9°C) in March.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 11 | 12 | 16 | 20 | 24 | 26 | 30 | 31 | 28 | 24 | 18 | 13 |
| Avg low (°C) | 3 | 3 | 6 | 11 | 15 | 20 | 24 | 24 | 21 | 15 | 9 | 4 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 11 | 3 |
| Feb | 12 | 3 |
| Mar | 16 | 6 |
| Apr | 20 | 11 |
| May | 24 | 15 |
| Jun | 26 | 20 |
| Jul | 30 | 24 |
| Aug | 31 | 24 |
| Sep | 28 | 21 |
| Oct | 24 | 15 |
| Nov | 18 | 9 |
| Dec | 13 | 4 |
How hot and cold Kokubu-matsuki 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, Kokubu-matsuki feels like about 36°C (around August 10). About 61 days a year carry some heat stress, peaking in August.
On the coldest nights, wind chill pulls the feels-like down to about -0°C (around January 28), with roughly 24 freezing days a year (feels-like at or below 0°C), worst in January.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°C) | 11 | 12 | 16 | 20 | 24 | 26 | 34 | 35 | 30 | 24 | 18 | 13 |
| Air high (°C) | 11 | 12 | 16 | 20 | 24 | 26 | 30 | 31 | 28 | 24 | 18 | 13 |
| Feels-like low (°C) | 0 | 1 | 5 | 10 | 15 | 20 | 24 | 24 | 21 | 15 | 9 | 2 |
| Air low (°C) | 3 | 3 | 6 | 11 | 15 | 20 | 24 | 24 | 21 | 15 | 9 | 4 |
| Feels-like high (°C) | Air high (°C) | Feels-like low (°C) | Air low (°C) | |
|---|---|---|---|---|
| Jan | 11 | 11 | 0 | 3 |
| Feb | 12 | 12 | 1 | 3 |
| Mar | 16 | 16 | 5 | 6 |
| Apr | 20 | 20 | 10 | 11 |
| May | 24 | 24 | 15 | 15 |
| Jun | 26 | 26 | 20 | 20 |
| Jul | 34 | 30 | 24 | 24 |
| Aug | 35 | 31 | 24 | 24 |
| Sep | 30 | 28 | 21 | 21 |
| Oct | 24 | 24 | 15 | 15 |
| Nov | 18 | 18 | 9 | 9 |
| Dec | 13 | 13 | 2 | 4 |
Average hourly temperature in Kokubu-matsuki
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 31°C, and coldest before dawn in January, near 3°C.
Kokubu-matsuki 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 | 11° / 3° | 80 | 8.3 | 10.2 | 2.8 |
| Feb | 12° / 3° | 102 | 9 | 10.8 | 3.3 |
| Mar | 16° / 6° | 157 | 12.9 | 11.8 | 4.6 |
| Apr | 20° / 11° | 181 | 11.8 | 12.8 | 5.9 |
| May | 24° / 15° | 205 | 11.7 | 13.6 | 6.4 |
| Jun | 26° / 20° | 488 | 19.9 | 14 | 4.8 |
| Jul | 30° / 24° | 299 | 19.4 | 13.9 | 3.9 |
| Aug | 31° / 24° | 174 | 18.3 | 13.2 | 3.8 |
| Sep | 28° / 21° | 202 | 15 | 12.2 | 5.2 |
| Oct | 24° / 15° | 114 | 9 | 11.2 | 7.1 |
| Nov | 18° / 9° | 107 | 8.2 | 10.4 | 6.2 |
| Dec | 13° / 4° | 81 | 7.1 | 10 | 4.0 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Kokubu-matsuki gets about 2188 mm of precipitation a year. On a typical day the chance of rain is often wet, but that rises and falls sharply with the seasons.
The wetter season lasts 3.9 months, from around May 28 to Sep 24, peaking in June at about 77% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Dec 25.
June is the wettest month by volume, with 488 mm over about 20 wet days; January is the driest, with 80 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 26 | 32 | 40 | 40 | 39 | 65 | 63 | 59 | 49 | 29 | 27 | 23 |
| Rain days | 8 | 9 | 13 | 12 | 12 | 20 | 19 | 18 | 15 | 9 | 8 | 7 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 26 | 8 |
| Feb | 32 | 9 |
| Mar | 40 | 13 |
| Apr | 40 | 12 |
| May | 39 | 12 |
| Jun | 65 | 20 |
| Jul | 63 | 19 |
| Aug | 59 | 18 |
| Sep | 49 | 15 |
| Oct | 29 | 9 |
| Nov | 27 | 8 |
| Dec | 23 | 7 |
Monthly rainfall
Over a full year, Kokubu-matsuki collects about 2188 mm of rain across 151 wet days — roughly 182 mm in an average month.
It doesn’t fall evenly. June is the wettest month with 488 mm, while January is the driest at just 80 mm. The three wettest months alone bring about 45% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 80 | 102 | 157 | 181 | 205 | 488 | 299 | 174 | 202 | 114 | 107 | 81 |
| Rain days | 8 | 9 | 13 | 12 | 12 | 20 | 19 | 18 | 15 | 9 | 8 | 7 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 80 | 8 |
| Feb | 102 | 9 |
| Mar | 157 | 13 |
| Apr | 181 | 12 |
| May | 205 | 12 |
| Jun | 488 | 20 |
| Jul | 299 | 19 |
| Aug | 174 | 18 |
| Sep | 202 | 15 |
| Oct | 114 | 9 |
| Nov | 107 | 8 |
| Dec | 81 | 7 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Kokubu-matsuki, 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 September 12 and lasts for 6.6 months, ending around March 31. The clearest month is December, when the sky is clear, mostly clear, or partly cloudy 58% of the time on average.
The cloudier part of the year begins around April 1 and lasts for 5.4 months, ending around September 11. The cloudiest month is June, when it is overcast or mostly cloudy 83% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 49 | 47 | 45 | 40 | 32 | 17 | 30 | 42 | 44 | 58 | 57 | 58 |
| Cloudier (%) | 51 | 53 | 55 | 60 | 68 | 83 | 70 | 58 | 56 | 42 | 43 | 42 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 49 | 51 |
| Feb | 47 | 53 |
| Mar | 45 | 55 |
| Apr | 40 | 60 |
| May | 32 | 68 |
| Jun | 17 | 83 |
| Jul | 30 | 70 |
| Aug | 42 | 58 |
| Sep | 44 | 56 |
| Oct | 58 | 42 |
| Nov | 57 | 43 |
| Dec | 58 | 42 |
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 15, brings about 14 h 06 min of light; the shortest, around December 14, only 9 h 54 min — a swing of roughly 4 h 12 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 10.2 | 10.8 | 11.8 | 12.8 | 13.6 | 14.0 | 13.9 | 13.2 | 12.2 | 11.2 | 10.4 | 10.0 |
| Sunrise (AM) | 7:22 | 7:06 | 6:34 | 5:54 | 5:25 | 5:15 | 5:26 | 5:46 | 6:06 | 6:26 | 6:52 | 7:15 |
| Sunset (PM) | 5:30 | 5:57 | 6:19 | 6:40 | 7:02 | 7:19 | 7:19 | 6:56 | 6:17 | 5:38 | 5:13 | 5:11 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 10.2 | 7:22 | 5:30 |
| Feb | 10.8 | 7:06 | 5:57 |
| Mar | 11.8 | 6:34 | 6:19 |
| Apr | 12.8 | 5:54 | 6:40 |
| May | 13.6 | 5:25 | 7:02 |
| Jun | 14.0 | 5:15 | 7:19 |
| Jul | 13.9 | 5:26 | 7:19 |
| Aug | 13.2 | 5:46 | 6:56 |
| Sep | 12.2 | 6:06 | 6:17 |
| Oct | 11.2 | 6:26 | 5:38 |
| Nov | 10.4 | 6:52 | 5:13 |
| Dec | 10.0 | 7:15 | 5:11 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Kokubu-matsuki averages about 9 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 2 and 14 days.
The sunnier stretch runs 7.0 months, from around Sep 24 to Apr 25. The sunniest month is October, with roughly 13 sunny days (mixed).
The greyest month is June, down near 3 sunny days — about 80% fewer than the October peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 10 | 9 | 9 | 9 | 7 | 3 | 5 | 7 | 7 | 13 | 13 | 12 |
| Sky | Mixed | Mixed | Mixed | Mixed | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Mixed | Mixed | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 10 | Mixed |
| Feb | 9 | Mixed |
| Mar | 9 | Mixed |
| Apr | 9 | Mixed |
| May | 7 | Gloomy |
| Jun | 3 | Gloomy |
| Jul | 5 | Gloomy |
| Aug | 7 | Gloomy |
| Sep | 7 | Gloomy |
| Oct | 13 | Mixed |
| Nov | 13 | Mixed |
| Dec | 12 | Mixed |
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 Kokubu-matsuki, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 4.9 months, from around May 20 to October 15. The muggiest month is July, when the air feels humid, muggy or worse about 100% of the time.
The most comfortable stretch runs from around October 16 to May 19, and February is the most comfortable month — the air is dry or comfortable 100% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 99 | 98 | 91 | 69 | 29 | 2 | 0 | 0 | 3 | 33 | 74 | 96 |
| Comfortable (%) | 1 | 2 | 8 | 20 | 32 | 9 | 0 | 0 | 7 | 26 | 16 | 3 |
| Humid (%) | 0 | 0 | 1 | 9 | 25 | 25 | 1 | 1 | 15 | 22 | 8 | 1 |
| Muggy (%) | 0 | 0 | 0 | 2 | 12 | 33 | 11 | 6 | 28 | 15 | 2 | 0 |
| Oppressive (%) | 0 | 0 | 0 | 0 | 1 | 28 | 66 | 65 | 42 | 5 | 0 | 0 |
| Miserable (%) | 0 | 0 | 0 | 0 | 0 | 3 | 22 | 28 | 5 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|---|---|---|
| Jan | 99 | 1 | 0 | 0 | 0 | 0 |
| Feb | 98 | 2 | 0 | 0 | 0 | 0 |
| Mar | 91 | 8 | 1 | 0 | 0 | 0 |
| Apr | 69 | 20 | 9 | 2 | 0 | 0 |
| May | 29 | 32 | 25 | 12 | 1 | 0 |
| Jun | 2 | 9 | 25 | 33 | 28 | 3 |
| Jul | 0 | 0 | 1 | 11 | 66 | 22 |
| Aug | 0 | 0 | 1 | 6 | 65 | 28 |
| Sep | 3 | 7 | 15 | 28 | 42 | 5 |
| Oct | 33 | 26 | 22 | 15 | 5 | 0 |
| Nov | 74 | 16 | 8 | 2 | 0 | 0 |
| Dec | 96 | 3 | 1 | 0 | 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.
Wind in Kokubu-matsuki is steady company: average speeds sit near 8 km/h — calm — in every month of the year, with no meaningful windy or calm season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 9 | 9 | 9 | 8 | 8 | 7 | 7 | 7 | 7 | 7 | 7 | 8 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 9 | calm |
| Feb | 9 | calm |
| Mar | 9 | calm |
| Apr | 8 | calm |
| May | 8 | calm |
| Jun | 7 | calm |
| Jul | 7 | calm |
| Aug | 7 | calm |
| Sep | 7 | calm |
| Oct | 7 | calm |
| Nov | 7 | calm |
| Dec | 8 | calm |
Hazard calendar for Kokubu-matsuki
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Kokubu-matsuki sits in the Pacific typhoon belt; the season peaks July–October.
Kokubu-matsuki's rainy season runs June–July, when most of the year's rain falls.
Best time to visit Kokubu-matsuki
To characterize how pleasant the weather is in Kokubu-matsuki throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around mid November, Kokubu-matsuki is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.
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 Kokubu-matsuki for general outdoor tourist activities run from mid April to early June and again from late September to late November, 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) | 2.9 | 3.3 | 4.6 | 5.9 | 6.4 | 4.9 | 3.9 | 3.8 | 5.2 | 7.1 | 6.2 | 4.0 |
| Rating | poor | poor | fair | good | good | fair | fair | fair | fair | good | good | fair |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 2.9 | poor |
| Feb | 3.3 | poor |
| Mar | 4.6 | fair |
| Apr | 5.9 | good |
| May | 6.4 | good |
| Jun | 4.9 | fair |
| Jul | 3.9 | fair |
| Aug | 3.8 | fair |
| Sep | 5.2 | fair |
| Oct | 7.1 | good |
| Nov | 6.2 | good |
| Dec | 4.0 | fair |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best times of year to visit Kokubu-matsuki for hot-weather activities run from mid May to early June and again from mid July to late October, with a peak score in the second week of October.
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 Kokubu-matsuki, 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 31°C), the essentials are light clothes, rain gear and sun protection. In the cold season around January (highs near 11°C), pack a warm layer and rain gear.
In August, Kokubu-matsuki sees daytime highs around 31°C and nights near 24°C. Pack light clothes and rain gear. Worth having: sun protection. About 18 days see rain.
Sea temperature near Kokubu-matsuki
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea at the nearest coast (about 42 km away) is warmest in August at about 28°C and coldest in February near 18°C.
It's comfortable for a long swim from Apr 24 to Dec 26 — about 8.1 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 19 | 18 | 18 | 20 | 21 | 24 | 27 | 28 | 27 | 25 | 23 | 21 |
| Comfort | Cool | Cool | Cool | Cool | Refreshing | Refreshing | Warm | Tropical | Warm | Warm | Refreshing | Refreshing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 19 | Cool |
| Feb | 18 | Cool |
| Mar | 18 | Cool |
| Apr | 20 | Cool |
| May | 21 | Refreshing |
| Jun | 24 | Refreshing |
| Jul | 27 | Warm |
| Aug | 28 | Tropical |
| Sep | 27 | Warm |
| Oct | 25 | Warm |
| Nov | 23 | Refreshing |
| Dec | 21 | Refreshing |
UV index (midday) in Kokubu-matsuki 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 Kokubu-matsuki peaks around June 23 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 3 (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) | 3 | 5 | 7 | 8 | 8 | 11 | 11 | 9 | 10 | 6 | 5 | 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 | 7 | High |
| Apr | 8 | Very high |
| May | 8 | Very high |
| Jun | 11 | Extreme |
| Jul | 11 | Extreme |
| Aug | 9 | Very high |
| Sep | 10 | Very high |
| Oct | 6 | High |
| Nov | 5 | Moderate |
| Dec | 3 | Moderate |
Average hourly UV index in Kokubu-matsuki
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 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) | 2.5 | 4.5 | 6 | 7 | 8 | 8.5 | 8.5 | 7.5 | 7.5 | 6 | 4.5 | 2.5 |
| UV ≥ 6 (h/day) | 0 | 0 | 2.5 | 4 | 4.5 | 6 | 6 | 5 | 5 | 2 | 0 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 2.5 | 0 |
| Feb | 4.5 | 0 |
| Mar | 6 | 2.5 |
| Apr | 7 | 4 |
| May | 8 | 4.5 |
| Jun | 8.5 | 6 |
| Jul | 8.5 | 6 |
| Aug | 7.5 | 5 |
| Sep | 7.5 | 5 |
| Oct | 6 | 2 |
| Nov | 4.5 | 0 |
| Dec | 2.5 | 0 |
Air quality in Kokubu-matsuki 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 Kokubu-matsuki is worst in April — around 23 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (October, 12 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) | 15 | 19 | 22 | 23 | 21 | 17 | 12 | 14 | 12 | 12 | 14 | 13 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 15 | Moderate |
| Feb | 19 | Moderate |
| Mar | 22 | Moderate |
| Apr | 23 | Moderate |
| May | 21 | Moderate |
| Jun | 17 | Moderate |
| Jul | 12 | Moderate |
| Aug | 14 | Moderate |
| Sep | 12 | Moderate |
| Oct | 12 | Moderate |
| Nov | 14 | Moderate |
| Dec | 13 | Moderate |
Growing season
Kokubu-matsuki is mild enough that a frost-free day stays more likely than not even in midwinter. Nights are reliably above freezing from about March 5 to December 11 (282 days); outside that window a hard frost is an occasional risk.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 79 | 82 | 94 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 99 | 88 |
| Frost nights | 31 | 28 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 17 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 79 | 31 |
| Feb | 82 | 28 |
| Mar | 94 | 0 |
| Apr | 100 | 0 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 100 | 0 |
| Nov | 99 | 0 |
| Dec | 88 | 17 |
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. Kokubu-matsuki banks about 2,767 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) | 0 | 0 | 34 | 159 | 291 | 382 | 514 | 535 | 438 | 295 | 116 | 3 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 0 |
| Feb | 0 |
| Mar | 34 |
| Apr | 159 |
| May | 291 |
| Jun | 382 |
| Jul | 514 |
| Aug | 535 |
| Sep | 438 |
| Oct | 295 |
| Nov | 116 |
| Dec | 3 |
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.
Kokubu-matsuki receives about 3.9 kWh/m² a day of solar energy on average — moderate — with a clear seasonal swing between 2.6 and 5.1 kWh/m².
The brighter stretch of the year lasts 3.0 months, from around Jun 30 to Sep 27. The brightest month is July, averaging about 4.7 kWh/m² (bright).
The dimmest month is December, down near 2.6 kWh/m² — roughly 44% less than the July peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 2.8 | 3.4 | 4.2 | 4.9 | 5.0 | 4.0 | 4.7 | 4.8 | 4.1 | 3.7 | 2.9 | 2.6 |
| Level | Moderate | Moderate | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Moderate | Moderate | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 2.8 | Moderate |
| Feb | 3.4 | Moderate |
| Mar | 4.2 | Bright |
| Apr | 4.9 | Bright |
| May | 5.0 | Bright |
| Jun | 4.0 | Bright |
| Jul | 4.7 | Bright |
| Aug | 4.8 | Bright |
| Sep | 4.1 | Bright |
| Oct | 3.7 | Moderate |
| Nov | 2.9 | Moderate |
| Dec | 2.6 | Moderate |
Where is Kokubu-matsuki?
Kokubu-matsuki sits at 31.7°N, 130.8°E, 0 m above sea level, in Japan. The nearest listed city is Kirishima, 1.0 km away.
Topography around Kokubu-matsuki
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Kokubu-matsuki.
Within 3 km, the terrain around Kokubu-matsuki has only modest variations in elevation — a maximum elevation change of 220 m around an average of 26 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 603 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,680 m.
The land around Kokubu-matsuki is covered by artificial surfaces (48%), trees (24%) and cropland (21%) within 3 km, trees (60%) and water (26%) within 16 km, and trees (55%) and water (36%) 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 Kokubu-matsuki (31.7333°, 130.7667°, 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).