Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors in Semelhe, Portugal, where the sun can shine brightly, particularly during the summer months. With a Mediterranean climate classified as Csb, UV levels can fluctuate dramatically throughout the day, peaking at a high of 11 between noon and 2 PM. Awareness of these UV levels is vital for sunburn prevention and sustaining skin health, as excessive exposure can lead to serious complications, including skin cancer. Take note of these readings to enjoy the beautiful Portuguese landscape while protecting yourself from the potential risks associated with UV radiation.
As the sun rises, the UV Index begins at a gentle 1 at 07:00 and 08:00, indicating minimal sun exposure risk. However, by 09:00, it jumps to 3 and continues to climb rapidly, reaching a significant 8 by 11:00. High noon brings the peak UV index of 10 at 12:00, followed by an intense 11 from 13:00 to 14:00, signaling a critical time for sun protection. As the afternoon wanes, the index starts to decline, dropping to 9 at 15:00, then decreasing to 7 at 16:00 and 5 by 17:00. Post-sunset, the index falls sharply to 3 at 18:00 and settles back at 1 as the day concludes at 19:00. This data underscores the importance of staying shielded from midday sun when the UV radiation is at its strongest.
| 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 | 11 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 9 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, so do the UV levels, which significantly impact skin safety for both visitors and residents. The UV Index starts low in January (2) and December (2), indicating a low risk for sunburn. However, as we move into the spring and summer months, particularly from March (6) to August (9), the risk escalates, with April (8) and the peak in June (11) classified as extreme. The high-risk months are primarily from April through August, where burn times are notably short, especially in June, with only 10 minutes until skin damage occurs. It is crucial for individuals during these months to take necessary precautions, such as wearing sunscreen, protective clothing, and limiting sun exposure, especially during peak hours. As fall approaches, the UV Index gradually decreases, but awareness remains essential for safe outdoor activities.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Semelhe | 2 | 4 | 6 | 8 | 9 | 11 | 10 | 9 | 8 | 6 | 4 | 2 |
| 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 |