Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors in San Luis, Mexico, where the sun shines brightly in a semi-arid climate (BSk) year-round. With UV levels peaking at 11 during midday, awareness of these radiation levels is essential for sunburn prevention and long-term skin health. By monitoring the UV Index, you can make informed decisions about sun exposure, ensuring you stay protected from harmful effects while enjoying the beautiful outdoors. Remember, the higher the UV Index, the greater the risk—so let’s stay informed and keep our skin safe!
The UV Index for the day presents a fascinating variation as the sun climbs higher in the sky. Starting from a gentle 1 at 07:00, the intensity gradually escalates, reaching a moderate 4 by 09:00. The peak hits at 12:00 and 13:00, soaring to an intense 11, indicating a significant risk of harm from unprotected sun exposure. As the afternoon unfolds, the index begins to decline, tapering to 8 at 15:00, and by the evening, it plummets back to a 1 by 18:00. This data serves as a reminder to stay vigilant about sun safety during those peak hours when UV exposure is at its highest!
| 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 | 10 | very high | 15 min |
| 15:00 | 8 | very high | 15 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 |
The UV Index experiences significant seasonal variations, peaking during the summer months. High-risk months for UV exposure are from May to August, when the UV Index consistently reaches levels categorized as extreme (11), indicating a burn time as short as 10 minutes. March and April also present high risks with very high indexes (8 and 10), where the burn time drops to 15 minutes. Visitors and residents are strongly advised to take protective measures during these months, such as wearing sunscreen, sunglasses, and protective clothing, and seeking shade during peak sun hours to minimize the risk of skin damage. As fall approaches, the risk decreases, with October seeing a high category (UV Index 7) but burn times lengthening to 25 minutes.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| San Luis | 4 | 6 | 8 | 10 | 11 | 11 | 11 | 11 | 10 | 7 | 5 | 4 |
| Guadalajara UVI | 9 | 11 | 14 | 14 | 14 | 13 | 13 | 13 | 13 | 12 | 9 | 8 |
| Iztapalapa UVI | 10 | 12 | 14 | 15 | 14 | 14 | 14 | 14 | 14 | 12 | 10 | 8 |
| Ecatepec de Morelos UVI | 10 | 12 | 14 | 15 | 15 | 14 | 14 | 13 | 14 | 12 | 10 | 8 |
| Mexico City UVI | 10 | 12 | 14 | 15 | 15 | 14 | 14 | 13 | 14 | 12 | 10 | 8 |
| Puebla UVI | 10 | 12 | 14 | 15 | 15 | 15 | 15 | 14 | 14 | 13 | 10 | 9 |