Last updated: May 3, 2025
In Koga, Japan, understanding the UV Index is crucial for protecting your skin and overall health as you navigate the city's vibrant outdoor life. During sunny days, UV levels can peak significantly, with readings soaring to 11 around noon, making sunburn risk exceptionally high. Awareness of these fluctuations helps residents and visitors alike to take precautionary measures against harmful UV radiation, ensuring a safer and more enjoyable experience in Koga's Cfa climate. By paying attention to the UV Index, you can protect your skin from long-term damage while fully embracing the beauty of the outdoors.
The UV Index today follows a dynamic trajectory, peaking dramatically as the sun climbs. Starting at a modest 1 at 07:00, it rises to 3 by 08:00 and then continues its ascent, reaching 5 by 09:00. The intensity escalates further, peaking at an impressive 11 at 12:00—a time when sun protection is crucial. As the afternoon wears on, the index moderately descends, dropping to 10 by 13:00 and gradually decreasing to 6 at 15:00. By 16:00, it falls to 4, before tapering off to 1 by 18:00 and remaining constant until 19:00. This hourly breakdown highlights the importance of being sun-smart during peak hours, especially when the index is at its highest!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 5 | moderate | 30 min |
| 10:00 | 8 | 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 | 9 | very high | 15 min |
| 15:00 | 6 | high | 25 min |
| 16:00 | 4 | moderate | 30 min |
| 17:00 | 2 | low | 45 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, seasonal changes in UV exposure highlight periods of heightened risk for residents and visitors. From January to February, the UV Index rises from 4 (moderate) to 6 (high), reducing safe exposure time to 25 minutes. Significant increases occur in March, reaching 8 (very high), and peaking during the summer months of April to August at 11-12 (extreme), where only 10 minutes of unprotected exposure is advisable. The risk, while still present, decreases again in September and returns to high levels in October and November with a UV Index of 6-7, allowing for 25 minutes of safe exposure. As such, it is crucial for visitors and residents to remain vigilant, especially during the summer, taking precautions like wearing sunscreen, protective clothing, and seeking shade during peak hours to mitigate the risk of UV-related health issues.
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 |
| 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 |
| Koga | 4 | 6 | 8 | 11 | 11 | 11 | 12 | 12 | 11 | 7 | 6 | 4 |