Last updated: August 1, 2025
In Shonai, Japan, being aware of the UV Index is crucial for protecting your skin and overall health. Understanding UV levels helps you prevent sunburns and reduces the risk of long-term skin damage. With a humid subtropical climate (Cfa), Shonai experiences significant UV exposure, especially during peak hours from 10 AM to 2 PM, where the index can soar to a striking 11. Staying informed about these levels empowers you to enjoy the outdoors safely while minimizing harmful effects from the sun.
The UV Index on this sunny day presents a compelling narrative of intensity and caution. Starting the morning gently at 2 by 7:00, the sun gradually escalates its strength, peaking at a robust 11 by 12:00. The midday hours are prime for sun-seekers, but with a UV Index hitting 10 at 11:00, it’s crucial to protect your skin. As the afternoon rolls in, the intensity diminishes, dipping to 5 by 15:00 and falling even lower to 1 by 17:00, making late afternoon and evening more suitable for outdoor activities without as much risk. However, as dusk approaches, the UV Index plunges to 0 by 19:00, marking a safe end to sun exposure. Embrace the sunshine wisely!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 4 | moderate | 30 min |
| 09:00 | 7 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 10 | very high | 15 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 8 | very high | 15 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, the UV Index demonstrates significant seasonal variation, impacting sun safety for residents and visitors. With moderate exposure levels in January and February (UV Index 3-4), individuals can safely enjoy outdoor activities with a burn time of 30 minutes. As we move into March, the UV Index reaches a high level of 6, reducing burn time to 25 minutes, and continues to escalate through April and May, where it peaks at very high levels of 9, necessitating a burn time of just 15 minutes. The extreme risk months of July and August, with a UV Index of 11, emphasize the need for heightened sun protection, allowing only 10 minutes of unprotected sun exposure. The UV Index decreases again in September to 9, remains at 6 in October, and returns to moderate levels in November and December. To ensure safety, visitors and residents should adopt protective measures—such as sunscreen and clothing—during the high-risk months of April through August, particularly on the most intense days when UV levels peak.
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 |
| Shonai | 3 | 4 | 6 | 9 | 9 | 10 | 11 | 11 | 9 | 6 | 4 | 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 |