Last updated: July 2, 2025
Understanding the UV Index is crucial for residents of Numata, Japan, where the climate in the Dfb zone brings distinct seasonal variations and daylight patterns. By keeping an eye on UV levels, you can effectively prevent sunburn and promote skin health, especially during peak hours when UV radiation is most intense. With maximum UV Index values reaching up to 9 from 11 AM to 12 PM, understanding these risks can help you enjoy the outdoors safely while protecting your skin from potential harm. Stay informed and embrace the sun wisely!
At 07:00, the UV Index begins at a modest 3, signaling a gentle start to the day. By 08:00, it climbs to 5, suggesting it's time to apply some sunscreen if you plan to be outdoors. As the sun reaches its peak around 10:00, the index hits a robust 8 and reaches its pinnacle at 11:00 and 12:00 with a peak of 9. This signifies a high risk of harm from unprotected sun exposure, making it crucial to seek shade or wear protective clothing during these hours. As the afternoon progresses, the index gradually decreases, dropping to 7 by 14:00, then to 4 at 15:00, and finally tapering off to 3 by 16:00. As the day winds down, the UV Index diminishes further, falling to 1 from 17:00 onward, indicating minimal risk for sun exposure. Stay safe and be sun smart!
| 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 | 4 | 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 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Numata | 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 |