Last updated: May 3, 2025
In San Marcos, United States, staying informed about the UV Index is crucial for safeguarding your skin against the harmful effects of ultraviolet radiation. Understanding the UV levels can help you take necessary precautions to prevent sunburn and maintain long-term skin health. With a Mediterranean climate characterized by sunny summers and moderate winters, San Marcos residents face heightened risks of UV exposure, especially during the peak hours between 10 AM and 2 PM when the index reaches as high as 11. By keeping an eye on the UV Index, you can enjoy the sunny outdoors while protecting yourself from potential harm.
The UV Index demonstrates a clear peak in intensity throughout the day, showcasing the need for sun protection during certain hours. Starting from a low of 1 at 07:00, the index rises steadily, reaching 4 by 09:00, before surging to a powerful 11 at midday. This intense level of UV radiation persists until 13:00, emphasizing the risk during these prime hours. As the afternoon progresses, the index gracefully declines, registering 9 at 14:00 and tapering off to a more moderate 3 by 17:00. By evening, it drops back to 1, signaling a safe window for outdoor activities as the sun sets. Be mindful of these fluctuations and stay protected during peak hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 4 | moderate | 30 min |
| 10:00 | 7 | high | 25 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV exposure varies significantly, with the highest UV Index levels observed from March to August. The months of May and June peak at an extreme UV Index of 11 and 12, where the burn time drops to just 10 minutes, posing a significant risk for sunburn. March and April also present substantial risks, classified as very high with an Index of 9 and 10, and a burn time of 15 minutes. As summer wanes into autumn, the UV Index begins to decrease, but September and October still remain at high levels with burn times of 15 to 25 minutes. Therefore, visitors and residents are strongly advised to prioritize sun safety, especially during the high-risk months of March through August by wearing protective clothing, using sunscreen, and seeking shade during peak sun hours.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chicago UVI | 3 | 4 | 6 | 8 | 9 | 10 | 10 | 9 | 8 | 6 | 4 | 2 |
| Brooklyn UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| New York City UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| San Marcos | 4 | 6 | 9 | 10 | 11 | 12 | 11 | 10 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |