UV Index in Koga, Japan

Last updated: May 3, 2025

Understanding the UV Index is crucial for residents and visitors in Koga, Japan, as it serves as a vital indicator of solar radiation exposure. High UV levels can lead to sunburns, skin damage, and long-term health issues, making it essential to stay informed. Koga boasts a Cfa climate, marked by hot summers and mild winters, which can elevate UV exposure risks significantly, especially during peak hours around 10 AM to 2 PM when the index reaches its maximum of 10. By being aware of the daily UV Index, you can take proactive measures to protect your skin and enjoy the beautiful weather safely.

Hourly UV Index in Koga

The UV Index shows a significant rise from 2 at 07:00 to a peak of 10 at 11:00 and 12:00, indicating the sun’s intensity is at its highest during these hours. As the day progresses, the index gradually declines, falling to 7 by 14:00 and dropping to 4 by 15:00. By late afternoon and evening, the UV exposure diminishes further, reaching 1 at 17:00 and 18:00, before tapering off to 0 by 19:00. This data emphasizes the importance of sun protection during the midday hours, particularly between 10:00 and 14:00, when UV radiation is most potent. Enjoy the sun responsibly!

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	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 Koga

The UV Index exhibits notable seasonal changes throughout the year, with high-risk months primarily occurring from March to September. March marks the shift to a high category (UV Index 7), while April and May escalate to very high (UV Index 9-10), culminating in extreme exposure levels during June and July (UV Index 11). As summer transitions to fall, the UV levels gradually decline, dipping to moderate levels by November and December. Visitors and residents should take necessary precautions, especially during the peak months of June and July, where the burn time is drastically reduced to just 10 minutes. It is advisable to wear protective clothing, apply sunscreen frequently, and seek shade during these high-risk times to minimize skin damage and health risks.

Monthly Maximum UV Index for Koga, Japan

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

The table above highlights how UV exposure in Koga 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.

Koga'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
Koga	3	5	7	9	10	11	11	10	9	6	5	3
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