Last updated: July 2, 2025
Understanding the UV Index in Iwanai, Japan, is essential for everyone who enjoys the outdoors in this beautiful region. With its Dfb climate, characterized by warm summers and cold winters, Iwanai presents unique challenges regarding UV exposure, especially during the peak hours when the UV Index can reach as high as 9. Awareness of UV levels not only helps in preventing sunburn but also plays a crucial role in maintaining long-term skin health. By staying informed about daily fluctuations in UV intensity, residents and visitors can make proactive decisions to protect themselves from potential skin damage while enjoying Iwanai’s stunning landscapes.
As the sun rises, the UV Index slowly climbs, starting at a gentle 2 by 07:00. By 08:00, it reaches 4, signaling it’s time to start protecting your skin. The intensity peaks around 11:00 and 12:00, hitting a maximum of 9, reminding everyone to seek shade and wear sunscreen. As the afternoon progresses, the index drops: it gently descends to 7 at 14:00, and continues its decline to 5 by 15:00. The latter part of the day sees a significant drop, with the index falling to 1 from 17:00 onwards, allowing for a safer evening outdoors. Stay vigilant during those midday hours, and enjoy the sun wisely!
| 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 | 8 | very high | 15 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 8 | 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 | 1 | low | 45 min |
Throughout the year, the UV Index reflects significant seasonal changes that impact exposure risks. January and December have low UV levels (Index 2), where burn times extend to 45 minutes. As spring approaches, by March the Index rises to 5, indicating moderate exposure risk. However, from April to September, the UV Index reaches high to very high levels, peaking at 10 in August, with burn times decreasing sharply to just 15 minutes. These months—April through September—pose the highest risk for sunburn, particularly May through August when the levels are consistently very high. Visitors and residents should prioritize sun protection during these months, recommending the use of sunscreen, hats, and protective clothing, and to seek shade during peak hours to minimize UV exposure. By October and November, the UV levels drop to moderate again, allowing for safer outdoor activities.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Iwanai | 2 | 3 | 5 | 7 | 9 | 9 | 9 | 10 | 8 | 5 | 3 | 2 |
| 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 |