Last updated: August 1, 2025
Understanding the UV Index in Niigata, Japan is crucial for anyone looking to protect their skin and health while enjoying the great outdoors. The UV Index serves as a vital indicator of the sun's intensity, helping residents and visitors alike prevent sunburn and long-term skin damage. With Niigata's Cfa climate, characterized by warm summers and moderate UV exposure, awareness of daily UV levels can make a significant difference in how you engage with outdoor activities. As high as 10 during midday hours, the UV index can pose risks if precautions aren’t taken—knowing when to seek shade or apply sunscreen is essential for safeguarding your skin health.
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 | 6 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 10 | very high | 15 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 |
As the year progresses, the UV Index in our region exhibits significant fluctuations, reflecting seasonal changes that are essential for visitors and residents to note. During the winter months of January and February, the UV Index remains in the moderate range (3-4), allowing for a burn time of about 30 minutes. However, as spring approaches, particularly in March, the UV Index rises sharply to high (7), reducing burn time to 25 minutes. The months of April through August present the highest risk, with UV Index values reaching very high (8-9) in April and May, escalating to a peak of extreme (11) in July and August, where the burn time drops to just 10 minutes. By September, there’s a slight decline to very high (9), and it further reduces in the fall months, with the index returning to the moderate range by November and December. Residents and visitors should take care during high-risk months—particularly from March through September—by seeking shade, wearing protective clothing, and using sunscreen to safeguard against harmful 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 |
| Niigata | 3 | 4 | 7 | 8 | 9 | 10 | 11 | 11 | 9 | 6 | 4 | 3 |
| 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 |