Last updated: June 2, 2025
Understanding the UV Index is vital for residents and visitors in Sai, Japan, a region known for its distinct Dfb climate. With UV levels peaking at 10 during midday, awareness of the sun's intensity is crucial for preventing sunburn and protecting your skin health. As Sai experiences varying weather conditions throughout the year, recognizing and monitoring UV exposure risks can empower you to enjoy outdoor activities safely while minimizing damage to your skin. Stay informed about the UV Index to safeguard yourself and your loved ones under the sun!
The UV Index today starts at a modest 3 at 7:00 AM, suggesting a gentle introduction to sunlight. As the day progresses, it rises sharply, peaking at an intense 10 during the 11:00 AM to 12:00 PM window. This means it’s crucial to protect your skin at this time! Following its midday zenith, the UV Index begins to decline, gently falling to 1 by 5:00 PM, and remaining low for the evening. If you're planning outdoor activities, aim for mid-morning as the sun reaches its highest intensity, but don’t forget your sunscreen!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 3 | moderate | 30 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 | 10 | very high | 15 min |
| 13:00 | 9 | 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 | 1 | 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 |
| Sai | 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 |