UV Index in Yokosuka, Japan

Last updated: June 2, 2025

In Yokosuka, Japan, staying informed about the UV Index is crucial for maintaining your skin health and preventing sunburn, especially during peak exposure hours. With a Cfa climate, residents and visitors alike face varying UV levels that can spike dramatically, reaching a maximum of 11 between 11:00 AM and 12:00 PM. This highlights the importance of understanding UV levels, as even short periods of unprotected sun exposure during these hours can lead to serious skin damage. By being aware of the UV Index, you can enjoy the beautiful Yokosuka outdoors safely while safeguarding your skin against harmful rays.

Hourly UV Index in Yokosuka

As the day unfolds, the UV Index rises sharply, peaking during the midday hours. At 07:00, it begins at a modest 2, but by 09:00, it escalates to 7, urging outdoor enthusiasts to take precautions. The sun reaches its zenith between 10:00 and 12:00, with the index soaring to a maximum of 11—a clear signal for sun safety measures. As the afternoon progresses, the intensity diminishes; by 14:00, it drops to 7, and further declines to 5 by 15:00. As daylight wanes, the index continues to fall, resting at 1 by 17:00 and tapering off to 0 post 19:00. This rhythmic rise and fall of UV exposure highlights the importance of midday vigilance against harmful rays.

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
08:005moderate30 min
09:007high25 min
10:0010very high15 min
11:0011extreme10 min
12:0011extreme10 min
13:0010very high15 min
14:007high25 min
15:005moderate30 min
16:003moderate30 min
17:001low45 min
18:001low45 min
19:000low45 min

Monthly UV Index Trends in Yokosuka

As the UV Index fluctuates throughout the year, residents and visitors should be particularly cautious during the high-risk months of March through August, when the UV Index reaches very high to extreme levels. In these months, the burn time decreases significantly to just 10-15 minutes. Specifically, May through August shows a consistent UV Index of 11, indicating extreme risk. Conversely, from January to February and in November to December, the UV Index is at a more moderate level (4-5), allowing for longer exposure times of 30 minutes. It is advisable to take protective measures such as wearing sunscreen, hats, and sunglasses, especially during midday hours when UV radiation is strongest. By staying informed and prepared, individuals can enjoy their time outdoors while minimizing the risk of UV-related health issues.

Monthly Maximum UV Index for Yokosuka, Japan

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Yokosuka. It measures the strength of ultraviolet radiation from the sun and helps assess the risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec458101111111110753
Data source: Statistical UV Index data for Yokosuka, 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 Yokosuka UV Index with Other Japan Cities

The table above highlights how UV exposure in Yokosuka 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.
Yokosuka's solar exposure compared to other cities in Japan. Generated using Copernicus Atmosphere Monitoring Service information.
 JanFebMarAprMayJunJulAugSepOctNovDec
Sapporo UVI2367999108532
Yokohama UVI35891111111110754
Tokyo UVI35891111111110754
Yokosuka458101111111110754
Nagoya UVI468101111111110753
Osaka UVI468111111121110753