Last updated: August 1, 2025
Understanding the UV Index is crucial for residents and visitors in Oma, Japan, where the climate often reflects the Dfb attribute—characterized by warm summers and cold winters. Awareness of UV levels helps you take necessary precautions to prevent sunburn and protect your long-term skin health. With midday UV Index values peaking at 10, the risks of overexposure are significant, especially during the summer months. By staying informed about local UV conditions, you can enjoy the region's beautiful outdoors while safeguarding your skin from harmful rays.
The UV Index throughout the day reflects a dynamic pattern of sun exposure. Starting at 7:00 AM with a low of 3, it gradually climbs to a moderate 4 by 8:00 AM. The real intensity kicks in at 9:00 AM, peaking at 10:00 AM with a maximum UV Index of 8. By 11:00 AM and 12:00 PM, the UV levels rise to 10, indicating high risk for harm from unprotected sun exposure. As the afternoon progresses, the Index begins to decline, with a noticeable drop to 9 at 1:00 PM and further to 7 by 2:00 PM. The sun’s intensity wanes as the day proceeds, plunging to 5 by 3:00 PM, and retreating to 3 at 4:00 PM. By 5:00 PM, the afternoon glow diminishes to 1, where it remains until 7:00 PM, highlighting a day that emphasizes the importance of sun protection during peak hours.
| 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 |
Throughout the year, UV index levels fluctuate significantly, indicating varying risks for sun exposure. January and December see low UV levels (Index 2), with extended burn times of 45 minutes, making sun safety less of a concern. In contrast, April to August marks a critical period with very high to extreme UV levels (Indexes 8 to 11) that dramatically decrease safe burn times to 15 minutes in April to July and just 10 minutes in August. May and June particularly stand out as high-risk months. As summer transitions into early fall, UV levels moderately decline but remain a risk with levels still at 8 in September, requiring continued vigilance. For optimal sun safety, visitors and residents are advised to monitor the UV index, especially during the high-risk months of April to August, adopting protective measures such as sunscreen, clothing, and shade to mitigate 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 |
| Oma | 2 | 3 | 5 | 8 | 9 | 10 | 10 | 11 | 8 | 6 | 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 |