Last updated: August 1, 2025
Understanding the UV Index is crucial for residents and visitors in Yuzawa, Japan, where daily exposure to harmful ultraviolet (UV) rays can significantly impact skin health. As you revel in the picturesque landscapes and outdoor activities this beautiful region offers, being aware of the UV levels, particularly during peak hours from 11 AM to 1 PM when the index reaches a maximum of 10, is vital for effective sunburn prevention and long-term skin protection. With Yuzawa's Cfa climate providing warm summers and moderate winters, the necessity to guard against intense UV radiation becomes even more critical, ensuring you can enjoy everything from skiing in winter to hiking in summer without compromising your skin's well-being.
The UV Index for the day starts off gently at 3 by 7:00 AM, gradually elevating as the sun climbs higher in the sky. By 9:00 AM, it reaches 7, signaling the onset of stronger rays. The peak occurs between 11:00 AM and 12:00 PM, where it hits a maximum of 10, indicating a high risk of harm from unprotected sun exposure. As the afternoon progresses, the index starts to decline, dipping to 5 by 3:00 PM and further to 1 by 5:00 PM, leading to a comfortable evening. As night falls at 7:00 PM, the UV index drops to 0, marking the end of sun-related concerns for the day. Remember to take precautions during peak hours to protect your skin!
| 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 | 10 | very high | 15 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 8 | very high | 15 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 |
Throughout the year, the UV Index experiences notable fluctuations, with high-risk months occurring between April and August. In April and May, the UV index peaks at 9, categorized as very high, requiring quick precautions with just 15 minutes of burn time. June and July sustain a UV Index of 10, also indicating very high levels, while August reaches an extreme UV Index of 11, minimizing safe sun exposure to just 10 minutes. In contrast, the UV levels are moderate from January to February and again from October to December, notably lowering burn times back to 30 minutes. Visitors and residents are strongly advised to protect their skin with sunscreen, hats, and protective clothing especially during the highest UV Index periods, ensuring they avoid prolonged sun exposure during peak hours. Stay informed and prioritize skin safety!
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 |
| Yuzawa | 3 | 4 | 6 | 9 | 9 | 10 | 10 | 11 | 9 | 6 | 4 | 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 |