Last updated: June 2, 2025
In Hokuryu, Japan, staying informed about the UV Index is crucial for protecting your skin from harmful ultraviolet radiation. Understanding UV levels helps residents and visitors alike prevent sunburn and maintain long-term skin health, especially in a region where the climate, classified as Dfb, can lead to significant solar exposure during peak hours. With the UV Index reaching as high as 9 around midday, knowing how to interpret these levels empowers you to enjoy the beautiful sun-drenched days while safeguarding your skin.
As the sun rises, the UV Index begins its ascent, reaching a modest 3 by 7:00 AM. However, as the morning matures, it quickly climbs to 5 at 8:00 AM and reaches a peak of 9 from 11:00 AM to 12:00 PM, indicating a high level of UV exposure. By 1:00 PM, the index starts to decline slightly to 8, and continues its descent until it falls to 5 by 3:00 PM. The afternoon sun starts to wane with values dropping to 3 by 4:00 PM, and by 6:00 PM, we're left with a minimal 1 for the rest of the evening. It's a vital reminder to protect your skin during those peak hours when the UV Index is at its highest!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 3 | moderate | 30 min |
| 08:00 | 5 | moderate | 30 min |
| 09:00 | 7 | high | 25 min |
| 10:00 | 8 | very high | 15 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 8 | very high | 15 min |
| 14:00 | 7 | high | 25 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 | 1 | low | 45 min |
The UV Index shows a clear seasonal variation, with high-risk months from March to September, where values peak at 10 in August. January and December experience low exposure with a UV Index of 2, while February and November have moderate exposure with an index of 3. During April and May, the UV Index rises significantly, reaching very high levels of 8 and 9, meaning a burn time of just 15 minutes is recommended during peak intensity months. Visitors and residents should take precautions from March through September, especially midday, to protect their skin, including wearing sunscreen, protective clothing, and seeking shade. As UV levels drop in the fall and winter, there is less risk, but some protection is still advisable in February and October.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hokuryu | 2 | 3 | 6 | 7 | 8 | 9 | 9 | 10 | 8 | 5 | 3 | 2 |
| 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 |