UV Index in Nagaoka, Japan

Last updated: June 2, 2025

Understanding the UV Index in Nagaoka, Japan is crucial for safeguarding your skin and overall health. As sun exposure can lead to harmful effects such as sunburn and long-term skin damage, being informed about UV levels allows residents to take necessary precautions. Nagaoka, characterized by its Cfa climate, experiences varied UV exposure throughout the day, with peak levels reaching 11 around noon. By staying aware of these fluctuations, you can enjoy the beautiful Japanese sun while prioritizing your skin's safety.

Hourly UV Index in Nagaoka

The UV Index exhibits a dynamic pattern throughout the day, peaking impressively at 12:00 PM with a striking value of 11, indicating a very high risk of harm from unprotected sun exposure. As early as 9:00 AM, the index jumps to 7, suggesting it’s time to start applying sunscreen. The intensity swells to 10 by 11:00 AM, urging sun safety measures. After reaching its zenith, the index gradually declines, dipping to 5 by 3:00 PM and eventually settling at a low of 0 by 7:00 PM. With these fluctuations, it’s crucial to be sun-smart, especially during 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	4	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	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 Nagaoka

Throughout the year, UV exposure varies significantly, peaking during the summer months. The highest risk for sunburn occurs from April to August, with the UV Index reaching extreme levels of 11 in both July and August, where the burn time is as short as 10 minutes. March marks the transition to higher UV levels, classified as high, and offers a burn time of 25 minutes. As spring progresses into summer, the risk escalates, with the very high category dominating from April through September, emphasizing the need for sun protection. Visitors and residents should take precautionary measures during these high-risk months, including wearing sunscreen, protective clothing, and seeking shade, especially during peak hours. As the year winds down, November and December return to a moderate UV Index (3-4), allowing for more time outdoors, but vigilance is still recommended.

Monthly Maximum UV Index for Nagaoka, Japan

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

The table above highlights how UV exposure in Nagaoka 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.

Nagaoka'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
Nagaoka	3	4	7	9	10	10	11	11	9	6	4	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