UV Index in Onna, Japan

Last updated: July 2, 2025

In Onna, Japan, understanding the UV Index is crucial for protecting your skin and overall health while enjoying the beautiful subtropical climate. As the sun rises higher, UV levels can reach alarming heights—peaking at 13 around midday—posing significant risks for sunburn and long-term skin damage. With its warm and sunny days typical of a Cfa climate, Onna residents and visitors alike must remain vigilant, ensuring they take the necessary precautions during peak hours. By staying informed about the UV Index, you can enjoy the sun safely and maintain your skin's health for years to come.

Hourly UV Index in Onna

The UV Index peaks dramatically throughout the day, starting from a gentle 1 at 07:00 and gradually rising to an impressive 13 by 12:00. This midday surge marks the day’s highest UV exposure, with levels reaching 11 at 11:00 and 13:00. As the sun begins to descend, the index declines smoothly, tapering back to 8 at 15:00, then 5 at 16:00, and finally settling down to 1 by 18:00 and 19:00. It's essential to stay protected, especially during those peak hours, as the sun’s rays can be quite fierce!

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	13	extreme	10 min
13:00	13	extreme	10 min
14:00	11	extreme	10 min
15:00	8	very high	15 min
16:00	5	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 Onna

Throughout the year, the UV Index exhibits significant fluctuations, with the highest levels occurring during the late spring and summer months. From February to September, the index reaches extreme highs, particularly in March to August, where the UV Index consistently sits at 13 with a minimal burn time of 10 minutes. The high-risk months are clearly identified as March through September, when individuals should take extra precautions. In contrast, January and December see lower UV levels, categorized as high with a burn time of 25 minutes, while October and November experience very high levels (UV Index 9) but allow slightly longer exposure (15 minutes). To ensure safety, residents and visitors are strongly advised to wear protective clothing, apply sunscreen frequently, and seek shade during peak sun hours in the high-risk months.

Monthly Maximum UV Index for Onna, Japan

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Onna. 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 Onna, 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 Onna UV Index with Other Japan Cities

The table above highlights how UV exposure in Onna 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.

Onna'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
Onna	7	9	11	12	13	13	13	13	12	9	9	6