Last updated: August 1, 2025
Understanding the UV Index is crucial for residents and visitors in Ajigasawa, Japan, where the region's Cfa climate brings significant sun exposure throughout the year. With peak UV levels reaching as high as 10 between 11:00 AM and 12:00 PM, awareness of these numbers can make all the difference in preventing sunburn and safeguarding your skin health. Given Ajigasawa's stunning landscapes and outdoor activities, it's essential to familiarize yourself with daily UV variations to enjoy the sun responsibly and protect yourself from the potential risks associated with high solar radiation.
During the early morning hours, the UV Index starts off mild, peaking at 3 by 7:00 AM. As the sun climbs higher, the intensity increases, hitting 4 by 8:00 AM and dramatically soaring to a peak of 10 at both 11:00 AM and 12:00 PM. This high level indicates a very high risk for harm from unprotected sun exposure. The afternoon brings a gradual decline, with the index dropping to 9 at 1:00 PM before easing down to 5 by 3:00 PM. As the sun sets, the UV Index gently recedes to 1 by 5:00 PM, ultimately falling to 0 by 7:00 PM, signaling a safe end to UV exposure for the day. Stay protected when the index is high, and enjoy the sun responsibly!
| 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 levels fluctuate significantly, with higher levels observed from March to September. The peak risk months are June, July, and August, where the UV Index reaches as high as 11, categorized as extreme, boasting a burn time of just 10 minutes. In spring, particularly April and May, the UV exposure escalates to very high levels (Index of 8-9), requiring heightened awareness. From October to March, UV Index values decrease, though residents and visitors should still take precautions in March (Index of 6) and October (Index of 6) due to higher risk levels. As a general guideline, it’s advisable to wear sunscreen and protective clothing, especially during peak hours, from March to August, to minimize sun exposure and reduce the risk of skin damage.
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 |
| Ajigasawa | 3 | 4 | 6 | 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 |