UV Index in Koshu, Japan

Last updated: May 3, 2025

In Koshu, Japan, staying informed about the UV Index is essential for maintaining healthy skin and preventing sunburn. With peak UV levels reaching 11 around midday, understanding these fluctuations can help residents and visitors protect themselves from harmful sun exposure. The Dfb climate of Koshu, characterized by distinct seasonal variations, can amplify UV risks, especially during summer months when the sun is most intense. By being aware of the UV Index, you can enjoy the beautiful outdoors while ensuring your skin stays safe and healthy.

Hourly UV Index in Koshu

The UV Index throughout the day reveals a dramatic rise in sun intensity, peaking at 11 around 11:00 AM and 12:00 PM. Starting from 07:00 AM with a low of 2, the index escalates rapidly, reaching 10 by 10:00 AM. As the sun climbs higher, it delivers its harshest rays, prompting caution for those outdoors. From 1:00 PM onward, the index gradually declines, hitting 5 at 3:00 PM, and finally tapering off to 0 by 7:00 PM. This profile highlights the importance of sun protection during the midday hours when UV exposure is most intense. Stay safe and protect your skin! 🌞

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	5	moderate	30 min
09:00	7	high	25 min
10:00	10	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	5	moderate	30 min
16:00	3	moderate	30 min
17:00	1	low	45 min
18:00	1	low	45 min
19:00	0	low	45 min

Monthly UV Index Trends in Koshu

Throughout the year, the UV Index demonstrates notable seasonal changes, with the most intense exposure occurring from April to August. During these months, the UV Index reaches extreme levels (10-12), significantly reducing the burn time to just 10 minutes. March and September also pose risks with very high levels (8-10), allowing for a burn time of only 15 minutes. Consequently, February and October present high levels (6-7), where protective measures are still advised with adjusted burn times of 25 minutes. Residents and visitors should exercise caution and protect their skin, especially during the high-risk months of April through August, by using sunscreen, wearing protective clothing, and limiting sun exposure during peak hours.

Monthly Maximum UV Index for Koshu, Japan

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

The table above highlights how UV exposure in Koshu 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.

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