Last updated: June 2, 2025
Understanding the UV Index is vital for residents and visitors of Hiranai, Japan, where the climate features a humid subtropical atmosphere. With daily UV levels frequently peaking at 10 around noon, awareness of these numbers is crucial for sunburn prevention and maintaining skin health. By grasping how UV exposure varies throughout the day—ranging from a moderate 2 at sunrise to a high-risk 9 and 10 during peak hours—individuals can better protect themselves and enjoy the beauty of Hiranai’s outdoor activities without compromising their well-being. Stay informed and safeguard your skin against the risks associated with this vibrant locale’s sunny days!
As the sun rises, the UV Index begins to climb steadily. At 7:00 AM, it registers a mild level of 2, but by 8:00 AM, it escalates to 4, indicating the start of a more intense sun exposure. The peak occurs at 11:00 AM and 12:00 PM, where it reaches a soaring 10, alerting everyone to take necessary precautions. After midday, the intensity starts to wane: it gently drops to 9 at 1:00 PM and gradually decreases to 5 by 3:00 PM. As the afternoon fades into evening, the UV Index dwindles to 3 at 4:00 PM and finally settles at 1 by 5:00 PM, bringing a close to the day's sun exposure risks. As night approaches, the UV Index drops to 0 after 7:00 PM, signifying a safe respite from the sun’s harsh rays.
| 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 | 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 | 0 | low | 45 min |
During the year, the UV Index exhibits significant seasonal fluctuations, with the highest levels occurring in summer months. From April to August, the UV Index reaches very high to extreme levels, peaking at 11 in August, where the recommended burn time is as little as 10 minutes. The high-risk months for UV exposure are April through August, necessitating extra precautions for both visitors and residents. To protect against harmful effects, individuals should wear protective clothing, apply sunscreen generously, and seek shade during peak sun hours. In contrast, January and December present lower UV indices, categorizing exposure as low, with longer burn times of up to 45 minutes. Staying informed about these changes can help ensure safe time spent outdoors throughout the year.
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 |
| Hiranai | 2 | 3 | 5 | 8 | 9 | 10 | 10 | 11 | 8 | 6 | 4 | 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 |