Last updated: August 1, 2025
Understanding the UV Index in Katagami, Japan is crucial for maintaining skin health and preventing sunburn, especially in a region with a humid subtropical climate (Cfa) that often sees significant solar exposure. With UV levels peaking at 10 around midday, even short outings can increase the risk of skin damage if proper precautions aren't taken. Awareness of these UV fluctuations, particularly during the peak hours from 10:00 AM to 2:00 PM, empowers residents and visitors alike to protect themselves from harmful rays, ensuring a healthier experience under the sun. So, whether you're enjoying the outdoors or planning a family outing, keep an eye on the UV Index to stay safe and sun-smart!
The UV Index throughout the day exhibits a distinct peak during the midday hours. Starting at 7:00 AM, the index is mild at 2, gradually rising to 4 by 8:00 AM. The intensity escalates sharply, reaching 7 by 9:00 AM and hitting its maximum of 10 at both 11:00 AM and 12:00 PM—a clear call for sun safety measures. As the afternoon unfolds, the index begins its decline: 9 at 1:00 PM, 7 at 2:00 PM, and dropping to 5 by 3:00 PM. By late afternoon, the UV intensity diminishes further to 3 at 4:00 PM and wanes significantly to 1 by 5:00 PM, ultimately falling to 0 by 7:00 PM. This data highlights the crucial hours for sun protection, especially around midday when the sun's rays are at their strongest.
| 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 | 10 | very high | 15 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 |
As the seasons change, so do the UV index levels and associated risks for skin damage. During the winter months of January to February, the UV index remains moderate (3-4), allowing for a 30-minute burn time. However, starting in March, the UV index escalates to high (6), indicating the need for increased sun protection. The high-risk months peak from April to August, with the UV index reaching very high (8-10) and even extreme levels (11) in August, where burn times drop to just 10 minutes. September sees a decline to very high (9), while October returns to high levels (6) with a longer burn time of 25 minutes. As winter returns in November and December, the sun's strength diminishes, with indexes dropping to moderate and low (4 and 2), leading to safer burn times of 30 and 45 minutes, respectively. It is crucial for visitors and residents to use sun protection consistently during high-risk months and limit direct sun exposure, especially during midday 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 |
| Katagami | 3 | 4 | 6 | 8 | 9 | 10 | 10 | 11 | 9 | 6 | 4 | 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 |