Last updated: July 2, 2025
Understanding the UV Index is crucial for residents and visitors in Fukushima, Japan, where the unique Dfb climate brings a mix of seasonal weather but also heightens exposure to harmful ultraviolet rays. Awareness of UV levels plays a vital role in preventing sunburn and promoting long-term skin health—an essential consideration, especially during the sunniest hours when the index peaks at a striking 11 around midday. As a city that experiences varied weather patterns, knowing how to protect yourself against the risks of overexposure is key to enjoying outdoor activities safely while preserving your skin health. Stay informed and enjoy the sun responsibly!
The UV Index throughout the day presents a clear peak between 11:00 AM and 12:00 PM, reaching a notable maximum of 11—a critical level necessitating protective measures from the sun. As the morning unfolds, the index rises steadily from 3 at 7:00 AM to a robust 9 by 10:00 AM, indicating increasing sun exposure. Following the midday high, there's a gradual decline, with values falling to 7 by 2:00 PM, before diminishing further to 3 by 4:00 PM. As evening approaches, the index drops significantly to 1 by 5:00 PM, and finally settles at 0 after 7:00 PM, marking the end of sun-related concerns for the day. For sun-seekers, midday is the time to either seize the sun responsibly or seek shade!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 3 | moderate | 30 min |
| 08:00 | 5 | 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 | 7 | high | 25 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 |
As the seasons change, so does the UV Index, which measures the strength of ultraviolet radiation. January and December start the year with a moderate UV Index of 3, allowing for a safer 30-minute exposure without significant risk. Moving into February, the index rises to 5, maintaining a moderate level, but caution is advised. By March, the UV Index escalates to 7 (high), warning of a 25-minute burn time. The most critical months for UV exposure are April through August, where the UV Index peaks at 11 (extreme), significantly lowering burn times to just 10 minutes in June, July, and August. September sees a drop to 9 (very high) with a 15-minute burn time, while October and November return to moderate levels, with indices of 6 and 5 respectively, allowing for longer exposure again. Therefore, visitors and residents should take precautions, particularly from April through August, using sunscreen, wearing protective clothing, and seeking shade to minimize UV exposure during these high-risk months.
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 |
| Fukushima | 3 | 5 | 7 | 9 | 10 | 11 | 11 | 11 | 9 | 6 | 5 | 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 |