Last updated: May 3, 2025
Understanding the UV Index in Nankoku, Japan is crucial for safeguarding your skin and overall health. With the region's Cfa climate, characterized by warm summers and mild winters, awareness of UV levels can help prevent sunburn and long-term skin damage. During peak hours, particularly between 11:00 AM and 1:00 PM, the UV Index can soar as high as 11, indicating a very high risk of harm from unprotected sun exposure. Staying informed about these levels means you can enjoy the beautiful Nankoku landscape while protecting your skin from the sun’s harmful rays. Remember to apply sunscreen, seek shade, and wear protective clothing when venturing outdoors, especially during those intense midday hours.
The UV Index begins its climb at 7:00 AM with a low level of 2, signaling a gentle start to the day. By 9:00 AM, it surges to 6, as the sun strengthens. The peak occurs around 11:00 AM to 1:00 PM, where it reaches a high of 11, indicating a need for sun protection. After this peak, the UV levels gradually decline, dipping to 9 by 2:00 PM and further to 3 by 4:00 PM. As the sun sets, the intensity decreases quickly, reaching 1 at 6:00 PM and finally dropping to 0 by 7:00 PM. This data highlights the midday hours as the most critical time for sun safety.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 6 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 6 | high | 25 min |
| 16:00 | 3 | moderate | 30 min |
| 17:00 | 2 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 0 | low | 45 min |
Throughout the year, the UV Index experiences significant fluctuations, with the highest risk months occurring from March to August, where it often reaches extreme levels. Notably, April, May, June, July, and August all register a UV Index of 12, indicating critical exposure levels with a burn time of only 10 minutes. Visitors and residents should take precautions during these months, such as wearing sunscreen, protective clothing, and seeking shade during peak sun hours. Conversely, from January to February and October to November, the UV levels are lower, categorized as moderate to high, allowing for a more comfortable outdoor experience, although caution is still advised. In December, the UV Index drops back to 4, reverting to a moderate category where burn time extends to 30 minutes, making it the safest month for outdoor activities. Overall, awareness of the UV Index can help individuals protect themselves from harmful sun exposure year-round.
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 |
| 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 |
| Nankoku | 4 | 6 | 9 | 11 | 11 | 12 | 12 | 12 | 10 | 7 | 6 | 4 |