Last updated: June 2, 2025
Understanding the UV Index is crucial for the residents of Yorii, Japan, as it serves as a vital tool in safeguarding skin health and preventing sunburn. With the region's Cfa climate contributing to varying levels of UV exposure throughout the day, knowing when the risk is at its peak—such as between 11:00 AM and 1:00 PM, when the UV Index surges to 11—can help you make informed choices about sun protection. With these high UV levels, awareness is key to enjoying the sun safely while minimizing potential long-term damage to your skin. Stay informed and protect yourself from the sun’s rays in this beautiful town!
As the sun rises, the UV Index begins its ascent, starting at a modest 2 at 7:00 AM. By 8:00 AM, it surges to 5, signaling the onset of midday sun exposure. The intensity peaks at 11 from 11:00 AM to 12:00 PM, making these hours crucial for sun protection. As the afternoon progresses, the index gradually declines, dipping to 9 at 1:00 PM, and then further to 7 by 2:00 PM. By late afternoon, at 5:00 PM, the UV Index drops to 5, and eventually settles at a low of 1 by 6:00 PM. Finally, as the sun sets, the UV Index returns to 0 by 7:00 PM. It's clear that during the peak hours of 11 AM to 12 PM, protective measures are highly recommended for safety under the sun.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 5 | moderate | 30 min |
| 09:00 | 7 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 9 | 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 | 0 | low | 45 min |
Throughout the year, UV exposure varies significantly, necessitating careful planning for both visitors and residents. The high-risk months for UV radiation are from March to August, with the UV Index peaking at an extreme level of 11 during May, June, July, and August, where the recommended burn time is just 10 minutes. In contrast, January, November, and December present a moderate UV Index of 3 to 5, allowing for longer exposure times of 30 minutes. To ensure safety, it is crucial to wear sunscreen, protective clothing, and sunglasses during the high-risk months, and to seek shade whenever possible to minimize skin damage from excessive UV radiation.
UV Risk Categories
| 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 |
| Yorii | 3 | 5 | 8 | 9 | 11 | 11 | 11 | 11 | 9 | 7 | 5 | 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 |