Last updated: June 2, 2025
Awareness of the UV Index in Niihama, Japan, is essential for anyone enjoying the outdoors, especially given the region's humid subtropical climate where UV levels can soar, particularly in the summer months. Understanding UV exposure is crucial for preventing sunburn and maintaining long-term skin health. With peak UV Index values reaching as high as 11 around midday, residents and visitors alike must be mindful of the risks associated with prolonged sun exposure. Stay informed to protect your skin and enjoy the sunny days in Niihama safely!
The hourly UV Index showcases a dynamic rise and fall throughout the day, peaking spectacularly around 11:00 AM and 12:00 PM, both hitting a maximum of 11, indicating a high risk of harm from unprotected sun exposure. As the day progresses, it starts at a gentle 2 at 07:00 AM, providing a calm introduction to the sun's intensity. By 9:00 AM, it reaches a moderate 6, and then scales up to its highest point by 10:00 AM with a reading of 9. As afternoon approaches, the index begins its decline, dropping to 6 at 15:00 PM before further easing into the evening with a 2 at 17:00 PM. By 18:00 PM and 19:00 PM, the UV levels settle at a safe 1, offering relief from the midday sun's intensity, making the late afternoon and evening much more inviting for outdoor activities. Stay sun-safe!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 4 | moderate | 30 min |
| 09:00 | 6 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 6 | high | 25 min |
| 16:00 | 4 | moderate | 30 min |
| 17:00 | 2 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV radiation levels dramatically fluctuate, impacting the risk of skin damage for both visitors and residents. The highest risk months occur from May to August, where the UV Index peaks at 11 to 12, indicating an extreme exposure category with a burn time of just 10 minutes. During these months, it is crucial to limit direct sun exposure and utilize protective measures such as sunscreen, hats, and clothing to safeguard skin health. March and April also present high levels of concern, categorized as very high with burn times of just 15 minutes. As seasons shift into fall and winter, the UV Index decreases, with December and January showing a moderate level, allowing for longer safe exposure times of 30 minutes. However, even during lower UV months, protective precautions are still advised. Stay informed and protect yourself year-round!
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 |
| Niihama | 4 | 6 | 8 | 10 | 11 | 11 | 12 | 12 | 10 | 7 | 6 | 4 |