UV Index in Karatsu, Japan

Last updated: July 2, 2025

In Karatsu, Japan, understanding the UV Index is essential for safeguarding your skin and overall health. With the potential for sunburn and long-term skin damage greatly increasing as UV levels rise, being aware of daily fluctuations in UV exposure is crucial. Karatsu, characterized by its Cfa climate, experiences significant UV radiation, especially during peak hours when the index can soar to 12. By staying informed about these levels, residents and visitors can take proactive measures to enjoy the sun safely while protecting their skin's health.

Hourly UV Index in Karatsu

The UV Index provides a clear snapshot of sun exposure throughout the day, peaking at 12 around noon. Starting the morning at a mild level of 1 at 07:00, the index swiftly climbs, reaching 11 by 11:00. The intensity plateaus at its highest point of 12 between 12:00 and 13:00, indicating a critical time for sun safety. As the afternoon progresses, the UVI declines, dropping to 10 at 14:00, and gradually softening to 4 by 16:00. By the evening hours, the index falls back to a comfortable 1 by 18:00, making later hours more forgiving for outdoor activities. Stay protected and plan your sun exposure wisely!

Average solar exposure data for the current time of the year. Actual values may vary and depend on many factors, such as cloud cover, vegetation cover, surface type, etc.
Time	UVI	Category	Time to Burn
07:00	1	low	45 min
08:00	3	moderate	30 min
09:00	5	moderate	30 min
10:00	8	very high	15 min
11:00	11	extreme	10 min
12:00	12	extreme	10 min
13:00	12	extreme	10 min
14:00	10	very high	15 min
15:00	7	high	25 min
16:00	4	moderate	30 min
17:00	2	low	45 min
18:00	1	low	45 min
19:00	1	low	45 min

Monthly UV Index Trends in Karatsu

The UV Index experiences significant fluctuations throughout the year, with the highest levels occurring from May to September, where it peaks at an extreme level of 12 in both July and August. This period marks the high-risk months for sun exposure, with a critical burn time of just 10 minutes. Conversely, the UV levels are more moderate in January and December, with a UV Index of 4 and a longer burn time of 30 minutes. Residents and visitors are advised to take proactive sun safety measures, particularly during the spring and summer months, including wearing sunscreen, protective clothing, and seeking shade during peak hours when the UV Index is highest.

Monthly Maximum UV Index for Karatsu, Japan

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Karatsu. It measures the strength of ultraviolet radiation from the sun and helps assess the risk of sunburn and UV-related health issues.

Data source: Statistical UV Index data for Karatsu, based on information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

Compare Karatsu UV Index with Other Japan Cities

The table above highlights how UV exposure in Karatsu compares to other major locations across Japan. This comparison helps travelers and residents better understand regional sun intensity and plan outdoor activities with sun safety in mind.

Karatsu's solar exposure compared to other cities in Japan. Generated using Copernicus Atmosphere Monitoring Service information.
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sapporo UVI	2	3	6	7	9	9	9	10	8	5	3	2
Yokohama UVI	3	5	8	9	11	11	11	11	10	7	5	4
Tokyo UVI	3	5	8	9	11	11	11	11	10	7	5	4
Nagoya UVI	4	6	8	10	11	11	11	11	10	7	5	3
Osaka UVI	4	6	8	11	11	11	12	11	10	7	5	3
Karatsu	4	6	8	10	11	11	12	12	11	7	6	4