Last updated: July 2, 2025
In Yachimata, Japan, being aware of the UV Index is crucial for protecting your skin and overall health under the sun. Understanding UV levels not only aids in preventing sunburn, it also plays a vital role in maintaining your long-term skin health. Yachimata's Cfa climate brings warm summers where UV exposure can peak, particularly between 10 AM and 2 PM, when indices soar to levels of 11—indicating a very high risk of harm from unprotected sun exposure. Be proactive and informed about the UV Index to enjoy the beautiful days while safeguarding your skin!
The UV Index throughout the day presents a dynamic picture of sun exposure. As early as 7:00 AM, the index starts at a mild 2, ramping up to a moderate 4 by 8:00 AM. The sun's intensity peaks around 11:00 AM and 12:00 PM with a striking 11, marking the height of caution for outdoor activities. As we move into the afternoon, the index gradually declines, dropping to 8 by 2:00 PM and further to 5 by 3:00 PM. The evening brings relief, with the UV Index decreasing to a 1 by 5:00 PM and finally hitting 0 by 7:00 PM. It’s clear that the midday hours pose the greatest risk, so sun safety measures are essential during those peak times.
| 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 | 11 | extreme | 10 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 8 | very high | 15 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 display significant seasonal changes, with the highest readings occurring from May to August, where the index reaches an extreme level of 11. This period signifies a high-risk for UV exposure, with a dangerously quick burn time of only 10 minutes. In contrast, the winter months of January, February, November, and December feature moderate UV levels, with indices ranging from 3 to 5 and a burn time of 30 minutes or more. Visitors and residents should take precautions during the peak months, particularly by seeking shade, wearing protective clothing, and applying sunscreen, as skin damage can occur rapidly during this time. It's crucial to remain vigilant during the spring and early fall as well, when UV levels are still notably high, especially in March and September.
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 |
| Yachimata | 3 | 5 | 8 | 9 | 11 | 11 | 11 | 11 | 9 | 7 | 5 | 4 |
| 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 |