Last updated: June 2, 2025
Awareness of the UV Index is crucial for residents and visitors in Uonuma, Japan, where the climate often brings warm summers and moderate sunshine. Understanding UV levels helps in effectively preventing sunburns and safeguarding skin health, particularly during peak hours when the UV Index soars to a maximum of 11 around midday. With Uonuma's Cfa climate, which combines humid subtropical conditions, it's essential to stay informed about UV exposure risks to enjoy outdoor activities while protecting your skin from harmful rays. Be proactive and check the UV Index regularly for a safer sun experience!
The UV Index reveals a striking pattern of sun exposure throughout the day. Starting at 7:00 AM, the index is a modest 2, but as the sun climbs higher, it reaches its peak intensity at 11:00 AM and 12:00 PM with a soaring 11—a clear signal to seek shade! By 1:00 PM, it dips slightly to 10, yet remains in the high-risk zone until 2:00 PM when it begins to wane to 8. The afternoon continues its descent, hitting 5 at 3:00 PM, before falling to a much safer 1 by 5:00 PM. By 7:00 PM, the UV Index plummets to 0, ushering in a welcome reprieve from the sun. If you’re planning outdoor activities, the early hours are best avoided, especially around midday when the UV exposure is at its peak!
| 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 | 10 | very high | 15 min |
| 14:00 | 8 | very high | 15 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 |
Throughout the year, UV Index values fluctuate significantly, indicating varying levels of sun exposure risk. The high-risk months for UV exposure occur from March to August, peaking during the summer months of June, July, and August with an extreme UV Index of 11 and a burn time as short as 10 minutes. Visitors and residents are strongly advised to take preventive measures during these months, such as wearing sunscreen with high SPF, protective clothing, and seeking shade whenever possible. As the year progresses, the UV Index decreases to a moderate level by November and December, allowing for safer outdoor activities, but caution is still essential, especially in early spring and late summer when burn times can still be relatively short. Remember to stay vigilant and protect your skin from harmful UV rays!
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 |
| Uonuma | 4 | 5 | 8 | 9 | 10 | 11 | 11 | 11 | 9 | 7 | 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 |