Last updated: July 2, 2025
In Kusatsu, Japan, staying informed about the UV Index is crucial for protecting your skin and overall health. Understanding UV levels helps you take proactive measures against sunburn and long-term skin damage, especially during the peak hours when the index skyrockets—reaching a maximum of 11 from 11:00 to 12:00. Kusatsu's Dfb climate brings a distinct seasonal variation, but sunny days can intensify UV exposure risks, making awareness and preventive actions essential for enjoying the beautiful outdoors safely. Remember, a little knowledge goes a long way in safeguarding your skin while you explore this charming hot spring town!
The UV Index reveals a striking pattern of sun exposure throughout the day. Starting at 7:00 AM, the index is a modest 2, but as the sun climbs higher, it reaches its peak intensity at 11:00 AM and 12:00 PM with a soaring 11—a clear signal to seek shade! By 1:00 PM, it dips slightly to 10, yet remains in the high-risk zone until 2:00 PM when it begins to wane to 8. The afternoon continues its descent, hitting 5 at 3:00 PM, before falling to a much safer 1 by 5:00 PM. By 7:00 PM, the UV Index plummets to 0, ushering in a welcome reprieve from the sun. If you’re planning outdoor activities, the early hours are best avoided, especially around midday when the UV exposure is at its peak!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 5 | moderate | 30 min |
| 09:00 | 7 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 11 | extreme | 10 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 | 1 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 0 | low | 45 min |
Throughout the year, UV exposure varies significantly, with the highest risk months being May through August when the UV Index reaches an extreme level of 11. During these months, the recommended burn time is reduced to just 10 minutes, necessitating vigilant sun protection practices. Notably, March and April also present high risk, characterized by very high UV indices of 8 and 9, respectively, with burn times of just 15 minutes. As UV levels taper off from September to December, residents and visitors should remain cautious, especially in the early months of spring. It’s vital for everyone to stay informed about UV levels and take appropriate protective measures, such as applying sunscreen, wearing protective clothing, and seeking shade, particularly during peak hours.
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 |
| Kusatsu | 4 | 6 | 8 | 9 | 11 | 11 | 11 | 11 | 10 | 7 | 5 | 3 |
| Osaka UVI | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 11 | 10 | 7 | 5 | 3 |