Last updated: May 3, 2025
In Okinawa, Japan, understanding the UV Index is crucial for maintaining skin health and preventing sunburns. With the island's Cfa climate, characterized by hot and humid summers, the sun's intensity can reach dangerously high levels, particularly between 10 AM and 2 PM when readings soar to a staggering UV Index of 13. Being aware of these UV levels empowers residents and visitors alike to take necessary precautions, ensuring enjoyable outdoor activities while safeguarding against the harmful effects of overexposure to sunlight.
The UV Index exposure throughout the day exhibits a striking progression, peaking at 13 around noon. Starting from a gentle 1 at 7 AM, the index gradually escalates, hitting 3 by 8 AM. As the morning unfolds, it climbs to 5 by 9 AM, reaching a significant 9 by 10 AM. The afternoon sun intensifies, culminating in a maximum value of 11 at 11 AM before surging to its zenith at 12 PM. Following the high point, the index gradually declines, dropping to 12 at 1 PM, and tapering off to 10, 7, and finally 4 by mid to late afternoon. As the sun sets, the UV Index diminishes further, resting at 1 by 6 PM and continuing through 7 PM. It’s advisable to take precautions during peak hours, especially between 11 AM and 1 PM, to ensure safety under the sun.
| 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 | 9 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 13 | extreme | 10 min |
| 13:00 | 12 | extreme | 10 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 7 | 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, the UV Index exhibits significant fluctuations, with the highest levels occurring during the late spring and summer months. From February to September, the index reaches extreme highs, particularly in March to August, where the UV Index consistently sits at 13 with a minimal burn time of 10 minutes. The high-risk months are clearly identified as March through September, when individuals should take extra precautions. In contrast, January and December see lower UV levels, categorized as high with a burn time of 25 minutes, while October and November experience very high levels (UV Index 9) but allow slightly longer exposure (15 minutes). To ensure safety, residents and visitors are strongly advised to wear protective clothing, apply sunscreen frequently, and seek shade during peak sun hours in the high-risk months.
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 |
| Okinawa | 7 | 9 | 11 | 12 | 13 | 13 | 13 | 13 | 12 | 9 | 9 | 6 |