Last updated: July 2, 2025
Understanding the UV Index is crucial for residents and visitors in Narutocho-mitsuishi, Japan, as it provides vital information about the intensity of ultraviolet radiation from the sun. This awareness is essential for preventing sunburn and protecting skin health, especially during peak hours when the index soars. With a Cfa climate, Narutocho-mitsuishi experiences warm summers and mild winters, leading to varied UV exposure risks throughout the year. Notably, during the sunniest hours, particularly between 11:00 AM and 1:00 PM, the UV Index reaches critical levels, emphasizing the need for effective sun protection strategies to ensure safe outdoor activities.
As the day unfolds, the UV Index climbs steadily, peaking at a striking 12 around noon, signaling a high risk for skin damage without protection. Early risers at 07:00 encounter a mild 2, but the intensity increases quickly, reaching 9 by 10:00 and a critical 11 by 11:00. From 12:00 to 13:00, the index holds its highest point at 12, making it essential to seek shade or apply sunscreen. After 13:00, the UV levels gradually decrease, dropping back to a manageable 4 by 16:00 and winding down to a safe 1 by 18:00. This hourly data serves as a reminder to take sun safety precautions, especially during peak hours.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 4 | moderate | 30 min |
| 09:00 | 6 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 12 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 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, the UV index experiences significant fluctuations, indicating varying levels of sun exposure risk. High-risk months are primarily from March to September, where UV indexes peak at 11 or 12, signaling extreme exposure levels and necessitating caution. Residents and visitors should be particularly vigilant during these months, with recommended burn times dropping to as low as 10 minutes in peak summer months. In contrast, the winter months of January, February, November, and December see moderate UV levels (index 4-5), with more manageable burn times of 30 minutes. To ensure safety, it’s advisable for individuals to wear protective clothing, apply sunscreen, and seek shade during peak UV hours, especially from late spring through early fall.
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 |
| Narutocho-mitsuishi | 4 | 5 | 8 | 11 | 11 | 11 | 12 | 11 | 10 | 7 | 5 | 4 |