Last updated: August 1, 2025
In Tokamachi, Japan, understanding the UV Index is crucial for safeguarding your skin and overall health. With summer temperatures in the humid subtropical climate zone (Cfa) often reaching high levels, awareness of UV exposure can help prevent painful sunburns and long-term skin damage. During peak hours, especially around 11:00 to 13:00, the UV Index soars to alarming levels of 11, indicating an extremely high risk for unprotected skin. By staying informed about UV levels, residents and visitors can take proactive measures to protect themselves, ensuring that fun in the sun remains safe and enjoyable.
The UV Index throughout the day presents a dynamic picture of sun exposure. As early as 7:00 AM, the index starts at a mild 2, ramping up to a moderate 4 by 8:00 AM. The sun's intensity peaks around 11:00 AM and 12:00 PM with a striking 11, marking the height of caution for outdoor activities. As we move into the afternoon, the index gradually declines, dropping to 8 by 2:00 PM and further to 5 by 3:00 PM. The evening brings relief, with the UV Index decreasing to a 1 by 5:00 PM and finally hitting 0 by 7:00 PM. It’s clear that the midday hours pose the greatest risk, so sun safety measures are essential during those peak times.
| 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 | 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 Index values fluctuate significantly, indicating varying levels of sun exposure risk. The high-risk months for UV exposure occur from March to August, peaking during the summer months of June, July, and August with an extreme UV Index of 11 and a burn time as short as 10 minutes. Visitors and residents are strongly advised to take preventive measures during these months, such as wearing sunscreen with high SPF, protective clothing, and seeking shade whenever possible. As the year progresses, the UV Index decreases to a moderate level by November and December, allowing for safer outdoor activities, but caution is still essential, especially in early spring and late summer when burn times can still be relatively short. Remember to stay vigilant and protect your skin from harmful UV rays!
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 |
| Tokamachi | 4 | 5 | 8 | 9 | 10 | 11 | 11 | 11 | 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 |