Last updated: July 2, 2025
Understanding the UV Index in Mashiko, Japan is essential for maintaining skin health and preventing sunburn. With the region's Cfa climate, characterized by warm summers and moderate sunlight, awareness of UV levels can help residents and visitors protect themselves from harmful rays. During summer peak hours, especially between 10:00 AM and 1:00 PM, the UV Index can reach as high as 11, indicating a very high risk of harm from unprotected sun exposure. By staying informed about UV levels, you can enjoy the beautiful outdoors of Mashiko while safeguarding your skin's health.
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 | 7 | high | 25 min |
| 10:00 | 10 | 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 | 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 | 0 | low | 45 min |
The seasonal changes in UV Index reveal significant variations throughout the year, with the highest levels occurring in the summer months. March marks the transition into the high-risk category with a UV Index of 7, and by April and May, it escalates to 9 and 10 respectively, indicating very high levels of UV radiation. July reaches its peak at an extreme level of 11, posing the highest risk for skin damage with a burn time of only 10 minutes. Post-summer in August and September, UV levels remain notably high, while October drops to a high level of 6, still warranting caution. January, February, November, and December exhibit moderate UV levels, with burn times allowing for more extended exposure without burns. For both visitors and residents, it is vital to take protective measures during the high-risk months of March to September, including wearing sunscreen, protective clothing, and seeking shade during peak hours to minimize UV exposure.
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 |
| Mashiko | 3 | 5 | 7 | 9 | 10 | 10 | 11 | 10 | 9 | 6 | 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 |