Last updated: May 3, 2025
In Hachijo, Japan, being aware of the UV Index is crucial for protecting your skin from harmful rays. With UV levels peaking at 11 during midday, understanding these metrics can be the difference between healthy skin and painful sunburn. As a Cfa climate region, Hachijo experiences warm summers that intensify UV exposure risks, particularly between 10:00 AM and 1:00 PM. By staying informed about the UV Index, residents and visitors can proactively safeguard their skin and enjoy the beautiful outdoors while minimizing health risks.
From sunrise to sunset, the UV Index reveals a compelling story of sun exposure. Starting at a mild 2 at 07:00, the index climbs steadily, reaching a peak of 11 by 12:00—a clear indication that it's time to slather on the sunscreen! As the sun nears its zenith, 10 at 10:00 and 11 at 11:00 signal intense UV radiation, making midday the most critical time for skin protection. By early afternoon, the value begins to wane, dropping to 7 at 14:00 before tapering off to 5 in the late afternoon. As daylight fades, the UV Index dwindles to 2 by 16:00, and ultimately settles at 0 by 19:00. It's a day that underscores the importance of being sun-smart, especially during those peak hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 5 | moderate | 30 min |
| 09:00 | 8 | very high | 15 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 | 2 | low | 45 min |
| 17:00 | 1 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 0 | low | 45 min |
During the year, the UV Index shows significant seasonal changes, peaking in the summer months. January and December have moderate UV levels (Index 4), with a burn time of 30 minutes. As spring approaches, February sees a rise to high levels (Index 6) and continues to climb sharply through March (Index 9), reaching April and May at extreme levels (Index 11). The highest UV readings occur in June and July (Index 12), accompanied by a burn time of just 10 minutes. As summer transitions to fall, the UV Index gradually decreases, with August still at extreme levels, followed by a slight drop in September (Index 10) and October and November returning to high levels (Index 6). It is crucial for residents and visitors to be particularly cautious during the high-risk months of April to August, taking protective measures such as wearing sunscreen, protective clothing, and seeking shade 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 |
| 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 |
| Hachijo | 4 | 6 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 7 | 6 | 4 |