Last updated: June 2, 2025
In San Antonio, understanding the UV Index is crucial for protecting your skin and maintaining overall health under the intense Texas sun. With a humid subtropical climate (Cfa), residents and visitors alike face significant exposure to harmful ultraviolet rays, especially during the peak hours of sunlight. The UV Index can reach a maximum of 12 around noon, indicating a high risk of sunburn and long-term skin damage. By staying informed about daily UV levels, you can take proactive steps to safeguard your skin, ensuring enjoyable outdoor activities without the painful aftereffects.
The UV Index throughout the day reveals a dynamic shift in sun intensity. In the early hours, from 7:00 to 9:00, the index remains low at 1 to 3, perfect for a leisurely morning stroll. However, as the sun climbs higher, the UV exposure peaks dramatically at 12:00 with an index of 10, reaching its highest point of 12 at 1:00 PM. This is the critical time for sun safety measures—sunscreen and protective clothing are essential! As the afternoon progresses, the intensity begins to wane, dropping to a 7 by 4:00 PM and further to a gentle 1 by 7:00 PM. Overall, it's a day marked by a sharp rise and gradual decline in UV levels, highlighting the importance of staying shielded during peak hours.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 3 | moderate | 30 min |
| 10:00 | 5 | moderate | 30 min |
| 11:00 | 8 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 12 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 10 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV levels exhibit significant seasonal changes. January sees a moderate UV Index of 5, while February and March jump to 8 and 9, respectively, indicating very high exposure risks with short burn times of just 15 minutes. The peak months for UV exposure are from April to August, where the Index reaches an extreme level of 11 to 12, necessitating caution with a burn time of only 10 minutes. As the year progresses, UV levels decrease, but October remains notably high at 9, followed by November with a high category of 7. For visitors and residents alike, it is crucial to take protective measures during the high-risk months of April through September and remain vigilant, using sunscreen, wearing protective clothing, and seeking shade to minimize the risk of skin damage.
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 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |
| San Antonio | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 12 | 11 | 9 | 7 | 5 |