UV Index in Seiyo, Japan

Last updated: June 2, 2025

In Seiyo, Japan, staying informed about the UV Index is crucial for protecting your skin and overall health. Understanding the daily UV levels can help you prevent sunburn and long-term skin damage, allowing you to enjoy the beautiful outdoors safely. With Seiyo's temperate Cfa climate, residents and visitors face varying UV exposure risks, particularly during the midday hours when the index peaks at an intense 11. By keeping an eye on the UV Index, you can take proactive steps to safeguard your skin while enjoying all that this picturesque region has to offer.

Hourly UV Index in Seiyo

The hourly UV Index showcases a dynamic rise and fall throughout the day, peaking spectacularly around 11:00 AM and 12:00 PM, both hitting a maximum of 11, indicating a high risk of harm from unprotected sun exposure. As the day progresses, it starts at a gentle 2 at 07:00 AM, providing a calm introduction to the sun's intensity. By 9:00 AM, it reaches a moderate 6, and then scales up to its highest point by 10:00 AM with a reading of 9. As afternoon approaches, the index begins its decline, dropping to 6 at 15:00 PM before further easing into the evening with a 2 at 17:00 PM. By 18:00 PM and 19:00 PM, the UV levels settle at a safe 1, offering relief from the midday sun's intensity, making the late afternoon and evening much more inviting for outdoor activities. Stay sun-safe!

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.
TimeUVICategoryTime to Burn
07:002low45 min
08:004moderate30 min
09:006high25 min
10:009very high15 min
11:0011extreme10 min
12:0011extreme10 min
13:0011extreme10 min
14:009very high15 min
15:006high25 min
16:004moderate30 min
17:002low45 min
18:001low45 min
19:001low45 min

Monthly UV Index Trends in Seiyo

The UV Index shows significant seasonal changes, with the highest levels of ultraviolet radiation occurring from March to September, characterized by very high to extreme exposure categories. March and April see UV Index values ranging from 9 to 10, while May through August peak at 12, indicating an extreme risk of harm from unprotected sun exposure, with a notably short burn time of just 10 minutes. July and August are particularly high-risk months, necessitating careful sun protection measures. As the months progress toward October, there is a decrease to 8, moving back to very high levels, while November and December return to high and moderate levels, respectively. To ensure safety, visitors and residents are strongly advised to adopt protective measures, such as using sunscreen, wearing protective clothing, and seeking shade during peak sun hours, particularly during the high-risk months of May through September.

Monthly Maximum UV Index for Seiyo, Japan

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Seiyo. It measures the strength of ultraviolet radiation from the sun and helps assess the risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec469101211121211764
Data source: Statistical UV Index data for Seiyo, 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 Seiyo UV Index with Other Japan Cities

The table above highlights how UV exposure in Seiyo 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.
Seiyo's solar exposure compared to other cities in Japan. Generated using Copernicus Atmosphere Monitoring Service information.
 JanFebMarAprMayJunJulAugSepOctNovDec
Sapporo UVI2367999108532
Yokohama UVI35891111111110754
Tokyo UVI35891111111110754
Nagoya UVI468101111111110753
Osaka UVI468111111121110753
Seiyo469101211121211864