Last updated: July 2, 2025
Understanding the UV Index in Honmachi, Japan is crucial for protecting your skin from harmful ultraviolet radiation. High UV levels, especially during the peak hours from 10 AM to 2 PM when the index reaches a maximum of 10, can lead to sunburn and long-term skin health issues. In Honmachi’s cool-summer humid continental climate, residents and visitors need to be particularly vigilant about UV exposure as they enjoy outdoor activities. Keep yourself informed and take preventive measures to safeguard your skin against the sun's intense rays.
As the sun rises, the UV Index begins its ascent, peaking spectacularly between 11:00 AM and 12:00 PM at a maximal value of 10, signaling a high risk for unprotected skin. Early morning hours, from 7:00 AM to 9:00 AM, see a gentle increase from a mild 3 to a moderate 7. However, by 10:00 AM, the intensity climbs sharply to 9, urging caution for sun exposure. After the midday zenith, the index gradually descends, dropping to 8 at 1:00 PM and continuing to fall until it reaches a minimal 0 by 7:00 PM. This data emphasizes the importance of sun safety, particularly during those peak hours when the sun’s rays are most potent.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 3 | moderate | 30 min |
| 08:00 | 5 | moderate | 30 min |
| 09:00 | 7 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 10 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 8 | very high | 15 min |
| 14:00 | 7 | high | 25 min |
| 15:00 | 4 | moderate | 30 min |
| 16:00 | 2 | low | 45 min |
| 17:00 | 1 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 0 | low | 45 min |
The UV Index varies significantly throughout the year, with high-risk months typically occurring from April to September, showcasing an index peaking at 10 in July. During these months, particularly in May through August, the exposure category is rated as very high with a burn time of just 15 minutes, signaling the need for heightened sun protection. Visitors and residents should be vigilant during this period, applying sunscreen regularly, wearing protective clothing, and seeking shade during peak sun hours. The index decreases in winter months, reaching a low of 2 in January and December, where protective measures can be relaxed, but moderation remains advisable to avoid any prolonged exposure even during low UV levels. Always check the local UV Index before heading outdoors, as conditions can change rapidly.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Honmachi | 2 | 3 | 5 | 7 | 8 | 9 | 10 | 9 | 8 | 5 | 3 | 2 |
| Sapporo UVI | 2 | 3 | 6 | 7 | 9 | 9 | 9 | 10 | 8 | 5 | 3 | 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 |