Last updated: June 2, 2025
In Nagoya, Japan, staying aware of the UV Index is crucial for protecting your skin and overall health. With UV levels frequently reaching a maximum of 11 around midday, understanding these fluctuations can help you prevent sunburn and more serious skin conditions. The Cfa climate of Nagoya brings distinct seasonal changes, but high UV exposure during peak hours—from 10:00 AM to 2:00 PM—poses significant risks year-round. Knowledge of UV levels empowers residents and visitors alike to take proactive measures against harmful sun exposure, ensuring sunny days are safe and enjoyable.
As the sun rises, the UV Index begins its ascent, starting at a moderate level of 2 at 07:00. By 08:00, it climbs to 4, signaling an increase in sun exposure. The index peaks at 11:00, reaching a high of 10, marking the day's most intense UV radiation. 12:00 sees an even sharper rise to 11, a reminder to seek shelter or don sunscreen if heading outdoors. After this zenith, the UV Index gradually descends, with 10 at 13:00 and steadily decreasing through the afternoon—8 at 14:00, 5 at 15:00, and finally dipping to 2 at 17:00. As daylight fades, the index drops to 1 by 18:00 and becomes negligible at 0 by 19:00, signaling the end of the day's UV intensity. Always remember to take precautions during those peak hours!
| 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 | 2 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 0 | low | 45 min |
Throughout the year, UV exposure varies significantly, peaking during the summer months. High-risk months for UV exposure are from March to August, when the UV Index reaches its maximum levels of 10 to 11 and the burn time is as brief as 10 minutes. Notably, May through August features extreme exposure, requiring diligent sun protection practices. As the year transitions into fall, September to November sees a decrease in UV levels, with October still posing a moderate risk. To ensure safety, visitors and residents are advised to wear protective clothing, use sunscreen, and seek shade during the peak sun hours, especially from late spring through summer when the threat of sunburn is greatest.
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 | 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 |