Last updated: August 1, 2025
In Itoigawa, Japan, staying informed about the UV Index is crucial for protecting your skin and overall health. As the sun rises higher in the sky, UV levels can fluctuate dramatically, peaking at an intense 11 around noon. Understanding these fluctuations is vital for preventing sunburn and reducing the long-term risk of skin damage. With Itoigawa’s Cfa climate, characterized by warm summers, residents and visitors should be particularly cautious on sunny days, as exposure risks can lead to harmful effects if proper precautions aren't taken. Make sure to check the UV Index regularly to enjoy the beautiful outdoor scenery safely!
As the sun rises, the UV Index begins its ascent, starting at a moderate level of 2 at 07:00. By 08:00, it climbs to 4, signaling an increase in sun exposure. The index peaks at 11:00, reaching a high of 10, marking the day's most intense UV radiation. 12:00 sees an even sharper rise to 11, a reminder to seek shelter or don sunscreen if heading outdoors. After this zenith, the UV Index gradually descends, with 10 at 13:00 and steadily decreasing through the afternoon—8 at 14:00, 5 at 15:00, and finally dipping to 2 at 17:00. As daylight fades, the index drops to 1 by 18:00 and becomes negligible at 0 by 19:00, signaling the end of the day's UV intensity. Always remember to take precautions during those peak hours!
| 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 | 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 values experience significant seasonal changes, indicating varying levels of sun exposure risk. January and December have moderate UV Indexes (3), suggesting a safer exposure time of 30 minutes. As we move into February and November, the UV Index rises to 5, still moderate, but caution is warranted with a similar burn time. From March to October, the UV Index escalates, reaching its peak between July and August at an extreme level of 11, where only a mere 10 minutes of exposure can lead to burns. April and May also present very high risk with indexes of 9 and 10, respectively, offering 15 minutes of allowed exposure. The fall months, including September with a UV Index of 9, still require vigilance. Visitors and residents are urged to take necessary precautions during high-risk months—especially from March through August—to protect their skin, such as seeking shade, wearing protective clothing, and applying broad-spectrum sunscreen regularly.
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 |
| Itoigawa | 3 | 5 | 7 | 9 | 10 | 10 | 11 | 11 | 9 | 6 | 5 | 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 |