Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors in Sanjo, Japan, where the climate typically features hot summers and moderate winters. With UV levels peaking at a significant 11 around midday, being aware of these fluctuations can be essential for preventing sunburn and protecting your skin health. As Sanjo experiences varying UV exposure throughout the day, particularly in the warmer months, taking precautions during high-risk hours can help you enjoy the outdoors safely while minimizing the risk of skin damage.
The UV Index exhibits a dynamic pattern throughout the day, peaking impressively at 12:00 PM with a striking value of 11, indicating a very high risk of harm from unprotected sun exposure. As early as 9:00 AM, the index jumps to 7, suggesting it’s time to start applying sunscreen. The intensity swells to 10 by 11:00 AM, urging sun safety measures. After reaching its zenith, the index gradually declines, dipping to 5 by 3:00 PM and eventually settling at a low of 0 by 7:00 PM. With these fluctuations, it’s crucial to be sun-smart, especially during peak hours!
| 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, UV exposure varies significantly, peaking during the summer months. The highest risk for sunburn occurs from April to August, with the UV Index reaching extreme levels of 11 in both July and August, where the burn time is as short as 10 minutes. March marks the transition to higher UV levels, classified as high, and offers a burn time of 25 minutes. As spring progresses into summer, the risk escalates, with the very high category dominating from April through September, emphasizing the need for sun protection. Visitors and residents should take precautionary measures during these high-risk months, including wearing sunscreen, protective clothing, and seeking shade, especially during peak hours. As the year winds down, November and December return to a moderate UV Index (3-4), allowing for more time outdoors, but vigilance is still recommended.
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 |
| Sanjo | 3 | 4 | 7 | 9 | 10 | 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 |