Karatsu in Spring
In spring (March, April and May), Karatsu sees average daytime highs around 17°C and overnight lows near 12°C, with 401 mm of rain over about 33 wet days across the season. It is the 3rd-warmest season and the 2nd-wettest season.
Over the season highs climb from about 12°C in early March to 22°C by late May. The sky is clear or mostly clear about 31% of the time across spring, and the air most often feels dry.
Spring is Karatsu's 3rd-best season to visit on our travel score. For the whole year in context, see Karatsu's year-round climate.
- Avg daytime high
- 17°C
- 3rd-warmest season
- Avg overnight low
- 12°C
- Rainfall
- 401 mm
- 33 wet days
- Avg wind
- 13 km/h
- Travel score
- 5.1
- 3rd-best season
- Months
- Mar · Apr · May
Temperature in Karatsu in Spring
Over the season highs climb from about 12°C in early March to 22°C by late May.
A typical spring day in Karatsu reaches about 17°C and drops to 12°C overnight. The warmest of the three months is May, the coolest March.
How spring really feels in Karatsu
Once humidity and wind are folded in, spring brings about 0 days that feel above 32°C and 0 that feel at or below 0°C.
spring sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Karatsu weather by month
How the three spring months (March, April and May) 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 | 9° / 6° | 77 | 11.8 | 1.2 | 10 | 1.9 |
| Feb | 10° / 6° | 78 | 10.3 | 0.8 | 10.8 | 2.2 |
| Mar | 13° / 8° | 124 | 11.6 | 0.2 | 11.7 | 3.5 |
| Apr | 17° / 12° | 134 | 11 | 0 | 12.8 | 5.3 |
| May | 21° / 16° | 143 | 10.3 | 0 | 13.7 | 6.4 |
| Jun | 24° / 20° | 277 | 14.7 | 0 | 14.2 | 5.8 |
| Jul | 28° / 24° | 260 | 15.4 | 0 | 14 | 5.1 |
| Aug | 29° / 26° | 162 | 13.7 | 0 | 13.2 | 4.9 |
| Sep | 26° / 22° | 179 | 12.6 | 0 | 12.2 | 6.2 |
| Oct | 22° / 18° | 103 | 8.1 | 0 | 11.2 | 7.1 |
| Nov | 17° / 13° | 95 | 9.3 | 0 | 10.3 | 5.5 |
| Dec | 12° / 8° | 81 | 11.1 | 0.3 | 9.8 | 3.0 |
Cloud cover in Spring
The sky is clear or mostly clear about 31% of the time across spring.
Chance of precipitation in Spring
Karatsu gets around 401 mm of rain over 33 wet days across spring. The line is the day-by-day chance of measurable precipitation.
Humidity in Spring
Most of spring feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Spring
Winds average 13 km/h across spring.
Sunrise & sunset in Spring
Daylight runs from about 11 h 12 min in early March to 14 hours by late May. The lit band spans sunrise to sunset each day.
Solar energy in Spring
Average shortwave solar energy reaching the ground each day across spring, about 4.9 kWh/m².
Hazard calendar for Karatsu
In spring, Karatsu overlaps its pacific typhoon and rainy season season. The full year is below, with each hazard's peak months called out.
Karatsu sits in the Pacific typhoon belt; the season peaks July–October.
Karatsu's rainy season runs April–September, when most of the year's rain falls.
Is spring a good time to visit Karatsu?
Our two travel scores rate spring for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
spring is a reasonable time to visit Karatsu for sightseeing.
What to pack for Karatsu in Spring
From spring's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In spring, Karatsu sees daytime highs around 17°C and nights near 12°C. Worth packing: a warm layer, rain gear and sun protection. About 33 days see rain.
Sea temperature near Karatsu in Spring
The nearest coast averages about 16°C across spring — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 22 km away) is warmest in August at about 27°C and coldest in February near 14°C.
It's comfortable for a long swim from Jun 8 to Nov 21 — about 5.5 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 16 | 14 | 14 | 16 | 18 | 21 | 24 | 27 | 25 | 23 | 21 | 18 |
| Comfort | Cool | Bracing | Bracing | Cool | Cool | Refreshing | Warm | Warm | Warm | Refreshing | Refreshing | Cool |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 16 | Cool |
| Feb | 14 | Bracing |
| Mar | 14 | Bracing |
| Apr | 16 | Cool |
| May | 18 | Cool |
| Jun | 21 | Refreshing |
| Jul | 24 | Warm |
| Aug | 27 | Warm |
| Sep | 25 | Warm |
| Oct | 23 | Refreshing |
| Nov | 21 | Refreshing |
| Dec | 18 | Cool |
UV index in Karatsu in Spring
Clear-sky midday UV across spring 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 Karatsu peaks around July 23 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 3 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 3 | 4 | 6 | 8 | 8 | 7 | 9 | 9 | 9 | 6 | 4 | 3 |
| Level | Moderate | Moderate | High | Very high | Very high | Very high | Very high | Very high | Very high | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 3 | Moderate |
| Feb | 4 | Moderate |
| Mar | 6 | High |
| Apr | 8 | Very high |
| May | 8 | Very high |
| Jun | 7 | Very high |
| Jul | 9 | Very high |
| Aug | 9 | Very high |
| Sep | 9 | Very high |
| Oct | 6 | High |
| Nov | 4 | Moderate |
| Dec | 3 | Moderate |
Air quality in Karatsu in Spring
Average fine-particle pollution (PM2.5) through the year — so you can see where spring falls, not just the annual average.
Air quality in Karatsu is worst in April — around 24 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (July, 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) | 17 | 20 | 24 | 24 | 21 | 16 | 11 | 11 | 12 | 11 | 14 | 13 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good | Good | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 17 | Moderate |
| Feb | 20 | Moderate |
| Mar | 24 | Moderate |
| Apr | 24 | Moderate |
| May | 21 | Moderate |
| Jun | 16 | Moderate |
| Jul | 11 | Good |
| Aug | 11 | Good |
| Sep | 12 | Good |
| Oct | 11 | Good |
| Nov | 14 | Moderate |
| Dec | 13 | Moderate |
Where is Karatsu?
Karatsu sits at 33.4°N, 130.0°E, 7 m above sea level, in Japan. The nearest listed city is Imarichō-kō, 21 km away.
Topography around Karatsu
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Karatsu.
Within 3 km, the terrain around Karatsu has only modest variations in elevation — a maximum elevation change of 218 m around an average of 38 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 899 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,318 m.
The land around Karatsu is covered by trees (41%), artificial surfaces (28%) and water (24%) within 3 km, trees (59%) and water (29%) within 16 km, and water (58%) and trees (29%) 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 Karatsu (33.4425°, 129.9697°, elevation 7 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.