Last updated: July 2, 2025
Awareness of the UV Index is crucial for residents and visitors in Tsushima, Japan, where the climate can lead to significant sun exposure. Understanding UV levels is essential not only for preventing sunburn but also for maintaining long-term skin health. With Tsushima's temperate climate in the Cfa zone, UV exposure can vary dramatically throughout the day, peaking at a dangerous 12 around noon. Being informed about these UV levels allows you to take necessary precautions, ensuring a safe and enjoyable experience under the sun.
As the sun rises, the UV Index starts off mild at 1 at 07:00, making it safe to enjoy the morning outdoors. By 08:00, it increases to 3, signaling the need for light protection. However, the real intensity kicks in as the clock strikes 10:00, with the index peaking at a robust 12 by 12:00 and 13:00. During these hours, the sun’s rays are at their strongest, reaching a maximum of 11 at 11:00. As afternoon transitions into evening, the index begins to decline, dropping to 10 at 14:00 and gradually falling to 1 by 19:00. To make the most of your day, plan your outdoor activities in the early morning or late afternoon for a safer experience under the sun!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 5 | moderate | 30 min |
| 10:00 | 8 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 12 | extreme | 10 min |
| 13:00 | 12 | extreme | 10 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 2 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index exhibits significant seasonal changes, with high-risk months primarily occurring from March to September. During these months, UV levels climb sharply, peaking at an extreme 12 in July and August, where the burn time is reduced to just 10 minutes. As summer transitions to fall, UV exposure slightly declines but remains notable, hitting 10 in April, May, and September, with burn times of only 15 minutes. Visitors and residents are strongly advised to take precautions during these high-risk months by wearing sunscreen, protective clothing, and sunglasses, particularly during midday when the sun's rays are most intense. From late fall through winter, while the UV Index drops to moderate levels (3-5), it's still important to remain cautious, especially if spending extended time outdoors.
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 |
| Tsushima | 4 | 5 | 7 | 10 | 10 | 11 | 12 | 12 | 10 | 7 | 5 | 3 |
| Osaka UVI | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 11 | 10 | 7 | 5 | 3 |