UV Index in Hiroo, Japan

Last updated: July 2, 2025

Understanding the UV Index is crucial for residents and visitors in Hiroo, Japan, where sun exposure can vary significantly throughout the day. With the Dfb climate characterized by distinct seasonal variations, the UV levels can peak dangerously high, particularly during midday hours when readings reach as much as 10. Awareness of UV levels is essential not only for preventing sunburn but also for safeguarding long-term skin health. As Hiroo locals enjoy the outdoors, knowing when to seek shade or apply sunscreen can make all the difference in staying safe under the sun.

Hourly UV Index in Hiroo

In the morning, the UV Index starts off relatively low, peaking at 3 by 7 AM. As the day progresses, it steadily climbs, reaching a notable high of 10 at both 11 AM and 12 PM—this is the time to be cautious! The index then begins to dip and falls back to a moderate level of 4 by 3 PM, before dwindling to 1 by 5 PM, and finally settling at 0 by 7 PM. For those enjoying outdoor activities, it’s essential to stay sun-smart during the mid-day hours when UV radiation is at its peak!

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	3	moderate	30 min
08:00	5	moderate	30 min
09:00	7	high	25 min
10:00	9	very high	15 min
11:00	10	very high	15 min
12:00	10	very high	15 min
13:00	9	very high	15 min
14:00	7	high	25 min
15:00	4	moderate	30 min
16:00	2	low	45 min
17:00	1	low	45 min
18:00	1	low	45 min
19:00	0	low	45 min

Monthly UV Index Trends in Hiroo

Throughout the year, the UV Index experiences significant seasonal variations, with the highest risk months typically spanning from March to September. During this period, particularly in April, May, June, July, and August, the UV Index reaches a peak of 10, indicating a very high exposure category and a burn time of just 15 minutes. Conversely, the months of January and December signify the lowest UV levels, with an index of 2 and a burn time of 45 minutes. Visitors and residents should take caution during the high-risk months, employing protective measures such as sunscreen, hats, and sunglasses when spending time outdoors, as even short exposure can lead to skin damage. Being vigilant about UV levels can help ensure safety while enjoying the sun.

Monthly Maximum UV Index for Hiroo, Japan

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

The table above highlights how UV exposure in Hiroo 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.

Hiroo'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
Hiroo	2	3	6	8	9	10	10	10	8	6	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