Last updated: May 3, 2025
Understanding the UV Index is crucial for residents of San Guillermo la Reforma, Mexico, a region that experiences a subtropical highland climate. The UV levels can escalate rapidly throughout the day, reaching a peak of 15 around midday, which poses significant risks for sunburn and long-term skin health. By being aware of the UV Index, you can take proactive measures to protect your skin from harmful UV radiation, ensuring your outdoor activities remain enjoyable and safe. With typical exposure risks increasing during the warmer hours, it’s important to stay informed and adjust your sun safety practices accordingly.
The UV Index data paints a vibrant picture of sunlight intensity throughout the day. Beginning with a mild UVI of 1 at 7:00 AM, the day starts gently, gradually climbing to 3 by 9:00 AM. However, as the sun reaches its zenith, the UVI skyrockets, peaking at an intense 15 between 1:00 PM and 2:00 PM. During these hours, it's crucial to take protective measures against harmful UV rays. As the sun begins to set, the index dips, dropping to 5 by 5:00 PM and returning to a safer 1 by 7:00 PM. This fluctuation highlights the importance of staying sun-smart during peak hours, especially between 11:00 AM and 2:00 PM when the UVI is at its highest.
| 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 | 6 | high | 25 min |
| 11:00 | 10 | very high | 15 min |
| 12:00 | 13 | extreme | 10 min |
| 13:00 | 15 | extreme | 10 min |
| 14:00 | 15 | extreme | 10 min |
| 15:00 | 13 | extreme | 10 min |
| 16:00 | 9 | very high | 15 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
During the year, seasonal UV changes show significant fluctuations, with highest UV levels occurring from February to October. This period includes several high-risk months for sun exposure, particularly from March to October, where the UV Index reaches extreme levels (14-15), with a burn time of just 10 minutes. Conversely, January, November, and December experience very high UV Index ratings (9-10), with longer burn times of 15 minutes. Visitors and residents are strongly advised to take extra precautions during these high-risk months, including wearing protective clothing, applying broad-spectrum sunscreen with an SPF of 30 or higher, and seeking shade during peak hours to minimize the risk of UV-related harm.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 |
| San Guillermo la Reforma | 9 | 12 | 14 | 15 | 15 | 15 | 15 | 14 | 14 | 13 | 10 | 8 |
| Puebla UVI | 10 | 12 | 14 | 15 | 15 | 15 | 15 | 14 | 14 | 13 | 10 | 9 |