Last updated: July 2, 2025
Understanding the UV Index in Yamaguchi, Japan, is crucial for ensuring your skin's health and preventing sunburn, especially during the peak sunlight hours. As the UV levels can soar to a maximum of 12 around midday, knowledge of these fluctuations can help you take proper precautions, particularly for outdoor activities. Yamaguchi's humid subtropical climate brings ample sunshine, making it essential to be aware of UV exposure risks—even on seemingly mild days. Stay informed and protect yourself to enjoy the beauty of Yamaguchi without the burn!
The UV Index throughout the day showcases a dynamic shift in sun intensity, peaking at 12 around noon. Beginning with a gentle 2 at 7:00 AM, the index steadily increases, hitting 11 by 11:00 AM as the sun climbs higher. By 12:00 PM, the sun reaches its zenith at 12, marking the highest UV exposure, making sun safety a priority. As the afternoon progresses, from 1:00 PM to 3:00 PM, the UV Index gradually decreases to 9 by 2:00 PM and 7 by 3:00 PM. The day winds down with a notable drop in intensity, returning to a mild 1 by 6:00 PM, emphasizing that the safest time to enjoy the sun is before noon or after 4:00 PM.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 2 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 6 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 12 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 4 | moderate | 30 min |
| 17:00 | 2 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As the year progresses, the UV Index reveals significant seasonal changes and highlights high-risk months for sun exposure. From January to February, the UV Index remains in the moderate range (4-5), with a burn time of 30 minutes. However, starting in March, the UV Index surges to 8, classified as very high, drastically reducing safe exposure time to just 15 minutes. The peak risk occurs between April and August, with the UV Index reaching up to 12 (extreme), necessitating protective measures after just 10 minutes of sun exposure. As summer transitions to fall, the UV Index begins to decline, with September still presenting a very high level (10), before settling into high levels in October and November (6-7) with safer burn times of 25 minutes. December marks the lowest UV levels at 3, re-entering the moderate range. Visitors and residents are advised to exercise caution during the high-risk months of April to August, employing sunscreen, seeking shade, and wearing protective clothing to minimize the risks associated with intense UV 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 |
| 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 |
| Yamaguchi | 4 | 5 | 8 | 11 | 11 | 11 | 12 | 12 | 10 | 7 | 6 | 3 |