UV Index in Hiroshima, Japan

Last updated: May 3, 2025

In Hiroshima, Japan, understanding the UV Index is crucial for safeguarding your skin and overall health. With rising UV levels during the day, particularly peaking at 11 between 11 AM and 1 PM, awareness can help you prevent sunburn and reduce the risk of long-term skin damage. Given Hiroshima's Cfa climate, characterized by hot, humid summers, the potential for harmful UV exposure is significant. By monitoring the UV Index, residents and visitors alike can take proactive measures to protect themselves while enjoying the outdoors, ensuring safe and healthy sun exposure.

Hourly UV Index in Hiroshima

At dawn, the UV Index starts off gently at 2 by 7:00 AM, gradually rising as the sun climbs higher in the sky. By 09:00 AM, it reaches a moderate 6, but the real intensity hits at 11:00 AM and 12:00 PM, peaking at 11—a stark reminder to stay protected from the sun's rays. As the afternoon rolls on, the index begins to taper off, dropping to 8 at 2:00 PM, then declining further to 6 by 3:00 PM. As the day winds down, the UV Index falls to a safe 1 by 6:00 PM, signaling a welcome reprieve from the sun's powerful influence. Always remember to take precautions during those peak hours!

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	2	low	45 min
08:00	3	moderate	30 min
09:00	6	high	25 min
10:00	8	very high	15 min
11:00	11	extreme	10 min
12:00	11	extreme	10 min
13:00	10	very high	15 min
14:00	8	very high	15 min
15:00	6	high	25 min
16:00	3	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 Hiroshima

Throughout the year, UV Index levels exhibit significant seasonal variation, with the highest risks occurring in the spring and summer months. From March to August, the UV Index reaches extreme levels, peaking at 12 in July and August, where the recommended burn time is just 10 minutes. The months of April and May also maintain an extreme UV Index of 11. Conversely, during January and December, UV exposure is at a moderate level with a UV Index of 4, allowing for a burn time of 30 minutes. For residents and visitors, it is crucial to be particularly cautious from March through September, taking protective measures like wearing sunscreen, protective clothing, and limiting sun exposure during peak hours. Remain vigilant and prioritize skin safety, especially during the high-risk months of April through August.

Monthly Maximum UV Index for Hiroshima, Japan

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

The table above highlights how UV exposure in Hiroshima 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.

Hiroshima'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
Hiroshima	4	5	8	11	11	11	12	12	10	7	6	4