Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of Urayasu, Japan, where the subtropical Cfa climate can result in significant sun exposure. The UV Index provides a clear indicator of the strength of ultraviolet radiation, helping locals protect themselves from sunburn and long-term skin damage. With peak values reaching 11 during midday hours, it’s vital to be proactive about skin health by monitoring daily UV levels. By being aware of these risks, residents can enjoy the beautiful sunny days while minimizing potential harm from harmful rays.
As the sun rises, the UV Index begins at a mild 2 at 7:00 AM, making it a gentle start to the day. However, by 8:00 AM, it escalates to a notable 5 and continues its upward trajectory, peaking at an intense 11 from 11:00 AM to 12:00 PM—a time when sun protection is crucial. In the early afternoon, the index begins to wane, dipping to 9 by 1:00 PM, before cascading down to 5 by 3:00 PM. The sun's intensity further decreases, leading to 3 at 4:00 PM and fading to a safe 1 by 5:00 PM. As evening falls, the UV Index drops to 0 by 7:00 PM, marking a serene end to a sun-filled day. Remember, peak UV exposure is brief but intense—stay protected during those heights!
| 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 | 10 | 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 |
The seasonal UV variations indicate a significant increase in UV exposure from winter to summer, with high-risk months emerging from April through August. During this period, the UV Index peaks at 11 (extreme), particularly in June, July, and August, where the burn time drops to just 10 minutes. Visitors and residents are advised to take precautionary measures during these months, such as seeking shade, wearing protective clothing, and applying sunscreen frequently. As the UV levels decrease in the fall and winter months, with indices dropping to 3 in January and December, the risk of sunburn diminishes. However, maintaining sun safety practices year-round remains essential for health and well-being.
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 |
| Urayasu | 3 | 5 | 7 | 9 | 10 | 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 |