Last updated: July 2, 2025
In Alter do Chao, Portugal, being aware of the UV Index is essential for maintaining skin health and preventing sunburn. With a Mediterranean climate characterized by warm summers and significant sun exposure, understanding the daily UV levels can help you plan your outdoor activities safely. For instance, during peak hours—especially between 12:00 PM and 3:00 PM—UV Index values soar to 10, indicating a high risk of harm from unprotected sun exposure. By staying informed about these levels, residents and visitors can enjoy the sun while protecting their skin from potential damage.
The UV Index for the day showcases a striking ascent in intensity, peaking during the afternoon hours. Starting from a low of 1 at 07:00 and 08:00, the index swiftly climbs to reach 3 by 09:00. By 10:00, it escalates to a moderate 5, but the real surge occurs between 11:00 and 14:00, hitting a maximum of 10—indicating a high risk of harm from unprotected sun exposure. As the day progresses, the UV Index gradually drops, retracting to 4 by 17:00 and further declining to 1 by 19:00. It's crucial to stay protected during those 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 | 7 | high | 25 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 9 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, so do UV radiation levels, significantly impacting sun safety for residents and visitors. From January to February, the UV Index remains at a moderate level (3-4), with a burn time of 30 minutes. In March, the index rises to 6, classifying it as high, with a reduced burn time of 25 minutes. The real risk begins in April, when the UV Index skyrockets to 9 (very high), with a burn time of just 15 minutes. The peak arrives during June, where the Index reaches 11, categorized as extreme, leading to a minimal burn time of 10 minutes. This elevated risk continues through July and August, before tapering off in September to a still significant 8, and returning to high levels of 6 in October. As UV levels decline in November and December, with indices dropping back to moderate (3-4), residents and visitors should take special care from April to September, practicing sun safety measures, including using sunscreen, wearing protective clothing, and seeking shade during peak hours.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Braga UVI | 2 | 4 | 6 | 8 | 9 | 11 | 10 | 9 | 8 | 6 | 4 | 2 |
| Porto UVI | 2 | 4 | 6 | 8 | 9 | 11 | 10 | 9 | 8 | 6 | 4 | 2 |
| Amadora UVI | 3 | 5 | 6 | 9 | 10 | 11 | 10 | 9 | 8 | 6 | 4 | 3 |
| Lisbon UVI | 3 | 5 | 6 | 9 | 10 | 11 | 10 | 9 | 8 | 6 | 4 | 3 |
| Setubal UVI | 3 | 5 | 6 | 9 | 10 | 11 | 10 | 9 | 8 | 6 | 4 | 3 |
| Alter do Chao | 3 | 4 | 6 | 9 | 10 | 11 | 10 | 10 | 8 | 6 | 4 | 3 |