Last updated: August 1, 2025
Understanding the UV Index in Iwai, Japan is crucial for safeguarding your skin health and preventing sunburn, especially during the peak hours of midday sun. The UV levels can reach a maximum of 11 between 11:00 AM and 1:00 PM, indicating an extreme risk of harm from unprotected sun exposure. With Iwai's Cfa climate, characterized by hot summers and plenty of sunshine, residents and visitors must be aware of how to protect themselves. Being informed about the UV Index not only enhances your outdoor experiences but also plays a vital role in promoting long-term skin health. Stay sun-smart and enjoy the beautiful days in Iwai!
As the day unfolds, the UV Index reaches its peak during midday, providing an insightful glimpse into the sun's intensity. Starting from a modest 2 at 7:00 AM, the index climbs steadily, hitting 4 by 8:00 AM. By 9:00 AM, it escalates dramatically to 7, before soaring to its maximum of 11 at both 11:00 AM and 12:00 PM. As the afternoon progresses, the UV levels begin to ease, decreasing to 10 at 1:00 PM, then drifting down to 7 by 2:00 PM, and further to 5 at 3:00 PM. The descent continues into the evening, with the index dropping to 3 at 4:00 PM and tapering off to 1 by 5:00 PM, before settling at 0 by 7:00 PM. This data serves as a reminder to stay sun-safe, particularly during those 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 | 10 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 9 | very high | 15 min |
| 14:00 | 7 | high | 25 min |
| 15:00 | 4 | moderate | 30 min |
| 16:00 | 2 | low | 45 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 seasonal changes, with January and December presenting the lowest levels (UV Index 3) and the summer months of June and July reaching peak levels (UV Index 11), categorized as extreme. April and May also have very high readings (UV Index 9-10), indicating a gradual increase in risk as spring progresses into summer. March, August, and September maintain a high risk for UV exposure (UV Index 7-9). Visitors and residents are advised to take precautions from March through October, especially during the extreme months of June and July, by seeking shade, wearing protective clothing, and applying sunscreen regularly, as burn times decrease significantly to as little as 10 minutes during peak UV periods.
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 |
| Iwai | 3 | 5 | 7 | 9 | 10 | 11 | 11 | 10 | 9 | 7 | 5 | 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 |