UV Index in Koga, Japan

Last updated: July 2, 2025

In Koga, Japan, staying aware of the UV Index is essential for maintaining skin health and preventing sunburn. With a typical Cfa climate, residents and visitors alike face varying UV exposure risks throughout the day. Understanding the daily UV levels—which can peak at a striking 12 between noon and 1 PM—is crucial for protecting your skin and enjoying the outdoors safely. By being informed about these levels, you can take proactive measures like applying sunscreen or seeking shade, ensuring you make the most of Koga's beautiful sunny days while keeping your skin safe from harm.

Hourly UV Index in Koga

During the morning hours, the UV Index starts off low at 1 at 7:00 AM, indicating minimal risk of harm from unprotected sun exposure. As the day progresses, the intensity ramps up, peaking at 12 around 12:00 PM and 1:00 PM, suggesting a high risk for harm, especially for those spending extended periods outdoors. Post-peak, the index gradually declines, dropping to 7 at 3:00 PM and further down to 1 by 7:00 PM, which indicates a return to minimal risk as the sun sets. For sun enthusiasts, midday offers the most intense UV radiation, making sun protection essential during those 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	1	low	45 min
08:00	3	moderate	30 min
09:00	6	high	25 min
10:00	9	very high	15 min
11:00	11	extreme	10 min
12:00	12	extreme	10 min
13:00	12	extreme	10 min
14:00	10	very high	15 min
15:00	7	high	25 min
16:00	4	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 Koga

Throughout the year, seasonal changes in UV exposure highlight periods of heightened risk for residents and visitors. From January to February, the UV Index rises from 4 (moderate) to 6 (high), reducing safe exposure time to 25 minutes. Significant increases occur in March, reaching 8 (very high), and peaking during the summer months of April to August at 11-12 (extreme), where only 10 minutes of unprotected exposure is advisable. The risk, while still present, decreases again in September and returns to high levels in October and November with a UV Index of 6-7, allowing for 25 minutes of safe exposure. As such, it is crucial for visitors and residents to remain vigilant, especially during the summer, taking precautions like wearing sunscreen, protective clothing, and seeking shade during peak hours to mitigate the risk of UV-related health issues.

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
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
Koga	4	6	8	11	11	11	12	12	11	7	6	4