Last updated: July 2, 2025
Understanding the UV Index in Lisbon, United States, is crucial for anyone looking to enjoy the outdoors while protecting their skin health. High UV levels, particularly during midday, can lead to severe sunburn and increase the risk of skin cancer. Lisbon experiences a Cfb climate, characterized by mild summers and moderate UV exposure, yet residents and visitors must remain vigilant, especially with peak UV Index readings reaching as high as 9 around noon. Staying informed about these levels helps to ensure safe sun practices, making your time under the sun not just enjoyable, but also safe.
The UV Index throughout the day presents a clear pattern of intensity, peaking at midday. Starting from a mild level of 1 at 07:00, the index rises steadily, reaching 2 by 08:00. The real surge occurs between 09:00 and 13:00, where it escalates from 4 to a striking 9—the highest point of the day. As the afternoon unfolds, the intensity slightly declines to 7 at 15:00, before tapering off to 5 at 16:00. The evening sees a further decrease, settling back to 2 by 18:00 and returning to 1 at 19:00. For those enjoying outdoor activities, it’s essential to take precautions, especially during the peak hours from 11:00 to 14:00 when the UV rays are most potent.
| 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 | 6 | high | 25 min |
| 11:00 | 8 | very high | 15 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 9 | very high | 15 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, the UV Index exhibits significant fluctuations, indicating varying levels of sun exposure risk. From January to March, the UV Index starts off in the moderate range (3-6), suggesting a burn time of 30 minutes in January and February, but decreases to 25 minutes in March. The high-risk months emerge from April to September, where the Index rises dramatically to the very high range (8-10), with a critical burn time dropping as low as 15 minutes in April, May, June, July, August, and September. October sees a decline back to a high UV Index (6), allowing for 25 minutes of exposure before burning, while November and December move back into moderate and low categories (4 and 2, respectively) with more forgiving burn times of 30 minutes and 45 minutes. Visitors and residents are strongly advised to take precautions during the high-risk months by wearing sunscreen, protective clothing, and seeking shade, particularly when the UV Index is at its peak in the summer months.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Lisbon | 3 | 5 | 6 | 8 | 9 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| 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 |