Last updated: May 3, 2025
Understanding the UV Index is crucial for residents of Katano, Japan, where the subtropical climate leads to significant sun exposure year-round. Knowing the daily UV levels helps protect against sunburn and promotes long-term skin health, allowing you to enjoy the outdoors safely. With peak UV ratings often reaching as high as 11 around midday, it’s essential to be proactive in shielding your skin during the summer months. By keeping an eye on the UV Index, you can make informed choices about outdoor activities while safeguarding your health against harmful ultraviolet rays.
The UV Index for the day follows a dynamic trend, peaking during the midday hours. Starting at a modest 2 at 7:00 AM, the intensity gradually intensifies, reaching 4 by 8:00 AM. As the sun climbs higher, the index escalates significantly, hitting a striking 9 at 10:00 AM and reaching its zenith of 11 at 12:00 PM. After this peak, a gradual decline sets in, with the index dropping to 5 by 3:00 PM before tapering off to 1 by 5:00 PM. The day concludes with a UV Index of 0 by 7:00 PM, signaling a clear drop in potential UV exposure. It's a reminder to stay sun-smart, especially during the midday hours when the UV rays are at their strongest!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 4 | moderate | 30 min |
| 09:00 | 6 | 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, with the highest levels observed from March to August, peaking at a UV Index of 12 in July. This period includes extreme levels of risk, where the recommended burn time is as little as 10 minutes. Visitors and residents should exercise caution during these months, particularly in April, May, June, and July, by seeking shade, wearing protective clothing, and using sunscreen. Conversely, January, November, and December present lower risk categories, with moderate exposure and longer burn times of 30 minutes. To ensure safety, it’s crucial to stay informed about the UV Index and adjust outdoor activities accordingly throughout the year.
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 |
| Katano | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 11 | 10 | 7 | 5 | 3 |
| Osaka UVI | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 11 | 10 | 7 | 5 | 3 |