Last updated: August 1, 2025
In Hirosaki, Japan, awareness of the UV Index is crucial for maintaining skin health and preventing sunburn. Understanding UV levels can help residents and visitors protect themselves from the harmful effects of UV radiation, especially during peak hours when the index reaches its highest points of 10 around 11:00 AM and 12:00 PM. With Hirosaki's humid continental climate, long summer days and increased UV exposure make it essential to be mindful of sun safety. Make informed choices to enjoy the beautiful outdoors while safeguarding your skin!
The UV Index for the day starts off gently at 3 by 7:00 AM, gradually elevating as the sun climbs higher in the sky. By 9:00 AM, it reaches 7, signaling the onset of stronger rays. The peak occurs between 11:00 AM and 12:00 PM, where it hits a maximum of 10, indicating a high risk of harm from unprotected sun exposure. As the afternoon progresses, the index starts to decline, dipping to 5 by 3:00 PM and further to 1 by 5:00 PM, leading to a comfortable evening. As night falls at 7:00 PM, the UV index drops to 0, marking the end of sun-related concerns for the day. Remember to take precautions during peak hours to protect your skin!
| 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 |
As the seasons change, so do the UV index levels and associated risks for skin damage. During the winter months of January to February, the UV index remains moderate (3-4), allowing for a 30-minute burn time. However, starting in March, the UV index escalates to high (6), indicating the need for increased sun protection. The high-risk months peak from April to August, with the UV index reaching very high (8-10) and even extreme levels (11) in August, where burn times drop to just 10 minutes. September sees a decline to very high (9), while October returns to high levels (6) with a longer burn time of 25 minutes. As winter returns in November and December, the sun's strength diminishes, with indexes dropping to moderate and low (4 and 2), leading to safer burn times of 30 and 45 minutes, respectively. It is crucial for visitors and residents to use sun protection consistently during high-risk months and limit direct sun exposure, especially during midday hours.
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 |
| Hirosaki | 3 | 4 | 6 | 8 | 9 | 10 | 10 | 11 | 9 | 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 |