Last updated: August 1, 2025
Understanding the UV Index in Isahaya, Japan is crucial for safeguarding your skin against harmful ultraviolet radiation. With peak levels soaring to 12 around midday, awareness of UV exposure is vital for preventing sunburns and maintaining long-term skin health. Isahaya’s temperate Cfa climate brings varying UV levels throughout the day, making it essential to monitor these fluctuations to enjoy the outdoors safely. By familiarizing yourself with the UV Index, you can take proactive measures to protect your skin while reveling in the region's beautiful sunny days.
The UV Index provides a clear snapshot of sun exposure throughout the day, peaking at 12 around noon. Starting the morning at a mild level of 1 at 07:00, the index swiftly climbs, reaching 11 by 11:00. The intensity plateaus at its highest point of 12 between 12:00 and 13:00, indicating a critical time for sun safety. As the afternoon progresses, the UVI declines, dropping to 10 at 14:00, and gradually softening to 4 by 16:00. By the evening hours, the index falls back to a comfortable 1 by 18:00, making later hours more forgiving for outdoor activities. Stay protected and plan your sun exposure wisely!
| 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 | 12 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 7 | 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 |