Last updated: July 2, 2025
Understanding the UV Index is essential for residents and visitors in Koster, South Africa, especially in the context of sun safety and skin health. Knowing the UV levels throughout the day helps in preventing sunburn and long-term skin damage, which can have serious health consequences. Koster's Cwa climate typically sees elevated UV exposure, particularly during peak daytime hours when the UV Index can rise to 6. Being aware of these levels allows you to take informed precautions, ensuring a fun and safe experience under the sun.
Throughout the day, the UV Index escalates to its peak between 12:00 PM and 1:00 PM, reaching a high of 6—a clear indicator to stay protected from the sun's rays. Early morning hours see a gentle start, with a maximum 1 at 7:00 AM and 8:00 AM, gradually rising to 2 by 9:00 AM. As the sun climbs, so does the intensity, spiking to 5 at 11:00 AM and maintaining a steady 6 for the peak hours. Following this brief burst of intensity, the UV Index dwindles swiftly, dropping to 4 by 2:00 PM, then further decreasing to 3 at 3:00 PM, and tapering off to 1 by 4:00 PM. Finally, as daylight fades, the index plummets to 0 by 6:00 PM, marking the end of a vibrant, sunlit day. Remember to stay safe and protect your skin, especially during midday hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 2 | low | 45 min |
| 10:00 | 4 | moderate | 30 min |
| 11:00 | 5 | moderate | 30 min |
| 12:00 | 6 | high | 25 min |
| 13:00 | 6 | high | 25 min |
| 14:00 | 4 | moderate | 30 min |
| 15:00 | 3 | moderate | 30 min |
| 16:00 | 1 | low | 45 min |
| 17:00 | 1 | low | 45 min |
| 18:00 | 0 | low | 45 min |
| 19:00 | 0 | low | 45 min |
Throughout the year, the UV Index indicates significant seasonal variations, with the highest values occurring from January to April, where it reaches an extreme level of 16 in January and December, with a burn time of just 10 minutes. February and March also maintain an extreme exposure category (UV Index 15 and 13 respectively), necessitating cautious sun protection measures. April sees a slight decrease to a UV Index of 11, still categorized as extreme. As the warmer months approach, the UV Index relaxes to 7 in May and 6 in June and July, classified as high, allowing for longer burn times of 25 minutes. However, August brings a spike back to a very high UV Index of 9, with a shorter burn time of 15 minutes. From September to November, we again encounter extreme UV levels, with indices hovering around 11 to 14 and consistent burn risks of 10 minutes. Visitors and residents are advised to exercise heightened sun safety measures, particularly during the high-risk months of January through April, and again in September through November, to prevent sunburn and skin damage. Regular application of broad-spectrum sunscreen, protective clothing, and seeking shade during peak sun hours are essential practices.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cape Town UVI | 14 | 13 | 11 | 8 | 5 | 3 | 4 | 6 | 9 | 11 | 12 | 14 |
| Durban UVI | 14 | 13 | 12 | 9 | 6 | 4 | 5 | 7 | 9 | 11 | 13 | 15 |
| Johannesburg UVI | 15 | 15 | 13 | 10 | 7 | 6 | 6 | 8 | 11 | 12 | 14 | 16 |
| Pretoria UVI | 16 | 15 | 13 | 10 | 7 | 6 | 6 | 9 | 11 | 13 | 14 | 16 |
| Soweto UVI | 16 | 15 | 13 | 11 | 7 | 6 | 6 | 8 | 11 | 13 | 15 | 16 |
| Koster | 16 | 15 | 13 | 11 | 7 | 6 | 6 | 9 | 11 | 13 | 14 | 16 |