Last updated: July 2, 2025
In Katsuyama, Japan, staying informed about the UV Index is crucial for ensuring your skin's health and preventing sunburn, especially during the summer months. Understanding UV levels can empower residents and visitors to take necessary precautions against harmful UV radiation, which peaks in the late morning and early afternoon hours. Given Katsuyama's Dfb climate, characterized by distinct seasons, the UV exposure risks can vary significantly throughout the year, but with UV Index levels soaring to 11 midday, awareness and protection are essential for enjoying the outdoors safely. Embrace the sun responsibly!
As the sun rises, the UV Index begins at a mild 2 by 07:00. It steadily escalates, reaching 4 at 08:00, and then surges to a peak of 11 between 11:00 and 12:00—this is when the sun is most intense. Vigilance is essential during these hours, as the risk of skin damage increases significantly. As the afternoon progresses, the UV levels gradually decline; 10 at 13:00, followed by a decrease to 8 at 14:00, a more manageable 6 at 15:00, and finally tapering off to 3 by 16:00. By 17:00, the index drops to 2, and the evening settles in with a minimal 1 by 18:00 and 19:00. It's a day of high UV exposure, urging outdoor enthusiasts to take precautions 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 | 11 | extreme | 10 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 8 | 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 | 1 | low | 45 min |
The UV Index experiences significant seasonal variations, peaking during the summer months. High-risk months for UV exposure are from May to August, when the UV Index consistently reaches levels categorized as extreme (11), indicating a burn time as short as 10 minutes. March and April also present high risks with very high indexes (8 and 10), where the burn time drops to 15 minutes. Visitors and residents are strongly advised to take protective measures during these months, such as wearing sunscreen, sunglasses, and protective clothing, and seeking shade during peak sun hours to minimize the risk of skin damage. As fall approaches, the risk decreases, with October seeing a high category (UV Index 7) but burn times lengthening to 25 minutes.
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 |
| Katsuyama | 4 | 6 | 8 | 10 | 11 | 11 | 11 | 11 | 10 | 7 | 5 | 4 |
| Osaka UVI | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 11 | 10 | 7 | 5 | 3 |