Last updated: May 3, 2025
Understanding the UV Index is crucial for residents of Isahaya, Japan, where the subtropical Cfa climate brings significant sun exposure, especially during summer months. Knowing the daily UV levels is essential for preventing sunburn and minimizing skin health risks, as ultraviolet radiation can lead to long-term damage even on seemingly mild days. With peak UV Index values in Isahaya reaching a striking 11 around noon, it’s important to take precautions to protect yourself during outdoor activities. Stay informed and stay safe under the sun!
At sunrise, the UV Index starts gently at 1 at 07:00, making it a safe time for morning activities. However, as the sun climbs higher, the intensity surges, reaching 3 by 08:00 and escalating to a peak of 11 between 12:00 and 13:00. This is the crucial window when protection from the sun is essential, as exposure can lead to skin damage. As afternoon progresses, the index gradually declines, settling back to 9 by 14:00. By the time evening approaches, the UV Index dips to 2 at 17:00 and returns to a minimal 1 by 18:00, signaling a return to safer levels. Whether you’re planning outdoor fun or just soaking up the sun, be mindful of these fluctuations for optimal UV safety!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 5 | moderate | 30 min |
| 10:00 | 8 | very high | 15 min |
| 11:00 | 10 | very high | 15 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 | 4 | moderate | 30 min |
| 17:00 | 2 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index exhibits significant seasonal variations, with spring and summer months posing the highest risk of UV exposure. From March to September, the index reaches very high to extreme levels—particularly during April to August, where it peaks at 12 in July and August. During these months, the burn time shortens dramatically to just 10 minutes, indicating a critical need for sun protection. Conversely, January and December record the lowest UV levels with a moderate exposure category, allowing for more extended exposure times of 30 minutes. Visitors and residents are advised to take precautions, especially from March to September, by wearing protective clothing, applying sunscreen, and seeking shade during peak hours to minimize the risks associated with high UV exposure.
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 |
| Isahaya | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 12 | 11 | 8 | 6 | 4 |