Last updated: May 3, 2025
Understanding the UV Index is crucial for residents and visitors in Mitoyo, Japan, where sun exposure can pose significant risks to skin health. With the region's Cfa climate, characterized by warm summers, the UV levels can reach peaks of 11 during midday hours—an indication of intense sunlight that can lead to sunburn and long-term skin damage. By keeping a close eye on the UV Index, you can effectively plan your outdoor activities and take necessary precautions to protect yourself from harmful rays, ensuring a fun and safe experience in this beautiful coastal city.
The UV Index early in the day starts off modest, peaking at 2 by 07:00 and climbing to a moderate 3 by 08:00. By 09:00, it surges to a robust 6, indicating increasing sun intensity. The heat reaches its zenith at 12:00, hitting an impressive 11, showing that midday is the prime time for sun exposure. As the afternoon progresses, the UV Index gradually declines, falling to 10 at 13:00, then to 8 by 14:00. By late afternoon, 15:00 sees it drop to 6, and as the sun sets, the index continues to taper off, descending to 3 by 16:00, and eventually settling at a low 0 by 19:00. It’s a day that underscores the importance of sun protection during peak hours, especially around noon.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | 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 | 8 | very high | 15 min |
| 15:00 | 6 | high | 25 min |
| 16:00 | 3 | moderate | 30 min |
| 17:00 | 2 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 0 | low | 45 min |
From January to December, UV Index values exhibit significant seasonal changes, peaking during the summer months. January and December maintain a moderate UV Index of 4, allowing for a burn time of 30 minutes. As spring arrives, March sees a notable increase to 8 (very high), reducing burn time to 15 minutes. The peak UV exposure occurs from May through August, where the index reaches a maximum of 12 (extreme), necessitating a burn time as brief as 10 minutes. September begins a gradual decline, returning to a very high level of 10, while October and November drop to moderate levels at 5. Visitors and residents should exercise caution from March to August, particularly during these high-risk months, by wearing protective clothing, applying sunscreen frequently, and seeking shade to limit 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 |
| Mitoyo | 4 | 5 | 8 | 10 | 11 | 11 | 12 | 12 | 10 | 7 | 5 | 4 |
| Osaka UVI | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 11 | 10 | 7 | 5 | 3 |