Last updated: May 3, 2025
Understanding the UV Index in Hayama, Japan, is crucial for protecting your skin and overall health. With peak UV levels reaching as high as 11 during midday hours, awareness of these risks can significantly help in preventing sunburn and long-term skin damage. Hayama's Cfa climate, characterized by mild summers and ample sunshine, means that residents and visitors alike must stay informed about UV exposure throughout the day. From the early hours when the index begins to rise, peaking around noon, being prepared can make all the difference for safe outdoor activities and maintaining healthy skin. Stay vigilant and enjoy the sun responsibly!
The UV Index throughout the day shows a stark rise as the sun climbs higher in the sky. Starting at a modest 2 at 07:00, it quickly escalates, hitting 5 by 08:00. The peak occurs between 11:00 and 12:00, reaching a significant 11, indicating a high risk for damage from unprotected sun exposure. As the afternoon progresses, the index gradually decreases, dropping to 9 at 13:00 and further to 7 by 14:00. By late afternoon, the UV levels decline sharply, returning to 5 at 15:00, followed by a mere 2 at 16:00. As the sun sets, the UV Index falls to 1 at both 17:00 and 18:00, and finally reaches 0 by 19:00, signaling a safe end to sun exposure for the day. Be cautious during the midday hours when the sun's rays are strongest!
| 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 | 9 | 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 |
As the UV Index fluctuates throughout the year, residents and visitors should be particularly cautious during the high-risk months of March through August, when the UV Index reaches very high to extreme levels. In these months, the burn time decreases significantly to just 10-15 minutes. Specifically, May through August shows a consistent UV Index of 11, indicating extreme risk. Conversely, from January to February and in November to December, the UV Index is at a more moderate level (4-5), allowing for longer exposure times of 30 minutes. It is advisable to take protective measures such as wearing sunscreen, hats, and sunglasses, especially during midday hours when UV radiation is strongest. By staying informed and prepared, individuals can enjoy their time outdoors while minimizing the risk of UV-related health issues.
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 |
| Hayama | 4 | 5 | 8 | 10 | 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 |