Last updated: May 3, 2025
Understanding the UV Index is crucial for residents and visitors in Unzen, Japan, where the climate brings both beauty and potential risks. With UV levels peaking at an alarming 11 during midday hours, awareness of these levels is vital for preventing sunburn and maintaining skin health. Unzen's Cfa climate typically features sunny days that heighten UV exposure, making it essential to keep track of the UV Index to enjoy outdoor activities safely. By staying informed, you can protect yourself and your loved ones from harmful effects while soaking in the stunning natural landscapes that Unzen has to offer.
As the sun rises, the UV Index starts at a mild 1 at 7:00 AM, perfect for early risers. By 8:00 AM, it increases to a moderate 3, hinting at the day ahead. Things heat up quickly, with the index peaking at an intense 11 around 12:00 PM, a reminder that sun protection is essential during midday. The UV levels maintain a strong presence, remaining at 10 at 1:00 PM before gradually tapering off to 9 by 2:00 PM. As the afternoon wanes, the UV Index drops to a cozy 6 at 3:00 PM and further descends to 4 by 4:00 PM. By the evening, the sun loses its intensity, with the index falling to 2 at 5:00 PM, and settling back to a safe 1 from 6:00 PM onward. This daily cycle underscores the importance of being sun smart, especially during peak hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 6 | high | 25 min |
| 10:00 | 8 | 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 | 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, seasonal changes in UV exposure highlight periods of heightened risk for residents and visitors. From January to February, the UV Index rises from 4 (moderate) to 6 (high), reducing safe exposure time to 25 minutes. Significant increases occur in March, reaching 8 (very high), and peaking during the summer months of April to August at 11-12 (extreme), where only 10 minutes of unprotected exposure is advisable. The risk, while still present, decreases again in September and returns to high levels in October and November with a UV Index of 6-7, allowing for 25 minutes of safe exposure. As such, it is crucial for visitors and residents to remain vigilant, especially during the summer, taking precautions like wearing sunscreen, protective clothing, and seeking shade during peak hours to mitigate the risk of UV-related health issues.
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 |
| Unzen | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 12 | 11 | 7 | 6 | 4 |