Last updated: July 2, 2025
In Yamagata, Japan, understanding the UV Index is crucial for maintaining skin health and preventing sunburn. With its Dfa climate, Yamagata experiences significant UV exposure, especially during the peak hours between 10 AM and 2 PM when the UV Index can soar to dangerous levels of 11. By keeping an eye on these UV levels, residents and visitors can take proactive steps to protect themselves from harmful rays. Awareness of the UV Index not only helps in planning outdoor activities safely but also promotes long-term skin care practices, ensuring a healthier lifestyle under the sun.
During the day, the UV Index experiences a significant peak, reaching a maximum of 11 between 11:00 AM and 12:00 PM, indicating a very high risk of harm from unprotected sun exposure. The index rises steadily from 3 at 7:00 AM to hit 9 at 10:00 AM, before surging past 10 just before noon. As the afternoon progresses, the intensity of UV rays begins to decline, dropping to 7 by 2:00 PM and further down to 5 by 3:00 PM. Transitioning into the evening, the threat diminishes significantly, with the UV Index plummeting to 1 by 5:00 PM and eventually reaching 0 after 7:00 PM. It's essential to take precautions during the peak hours to protect your skin from harmful UV radiation!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 3 | moderate | 30 min |
| 08:00 | 4 | 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 |
Throughout the year, the UV Index experiences significant fluctuations, peaking during the summer months. January and December see a moderate UV Index of 3, with a burn time of 30 minutes. As early as February, the Index rises to 5, indicating a continued moderate exposure. However, March marks the onset of high risk with an Index of 7, reducing burn time to 25 minutes. The real concern arises from April to August, where the Index reaches very high (9-10) and even extreme levels (11) in July and August, with dangerously short burn times of just 10-15 minutes. The season begins to taper off in September (UV Index 9) and October (UV Index 6), before returning to moderate levels in November and December. For visitors and residents, it is crucial to take protective measures, especially from April to August, by seeking shade, wearing protective clothing, and applying sunscreen rigorously to prevent harmful 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 |
| Yamagata | 3 | 5 | 7 | 9 | 10 | 10 | 11 | 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 |