Last updated: July 2, 2025
Understanding the UV Index is essential for residents and visitors in Les Ulis, France, particularly as the region enjoys a temperate Cfb climate with varying UV exposure throughout the day. Being aware of UV levels is crucial for preventing sunburn and maintaining long-term skin health. During peak hours, especially from 12 PM to 3 PM, the UV Index can climb to 8, indicating a significant risk of harm from unprotected sun exposure. By staying informed about UV levels, you can take the necessary precautions to enjoy the sun safely while protecting your skin.
The UV Index today presents a dynamic range, peaking during the midday hours. Starting off gentle in the morning, with 1 at both 07:00 and 08:00, the index gradually climbs to 2 by 09:00. As the sun reaches its zenith, the intensity soars, hitting 6 at 11:00 and peaking at an impressive 8 from 13:00 to 15:00. This indicates a critical time for sun protection, as the index then begins its decline, dropping to 6 by 16:00 before tapering off further to 3 by 18:00 and 2 at 19:00. Stay safe and enjoy the outdoors while being mindful of the sun’s rays!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 2 | low | 45 min |
| 10:00 | 4 | moderate | 30 min |
| 11:00 | 6 | high | 25 min |
| 12:00 | 7 | high | 25 min |
| 13:00 | 8 | very high | 15 min |
| 14:00 | 8 | very high | 15 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 2 | low | 45 min |
Throughout the year, UV levels vary significantly, with the highest risk months occurring from May to August, where the UV Index reaches a peak of 9 in June and remains at 8 during July and August, indicating a very high exposure category and a critical burn time of just 15 minutes. In contrast, winter months see much lower UV levels, with January and November registering a UV Index of 2 and December dropping to 1, categorized as low exposure. Visitors and residents should exercise caution during the high-risk months by minimizing sun exposure, wearing protective clothing, and applying sunscreen regularly, particularly between late spring and early fall when UV radiation is at its strongest.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Les Ulis | 2 | 3 | 5 | 6 | 8 | 9 | 8 | 8 | 6 | 4 | 2 | 1 |
| Paris UVI | 2 | 3 | 5 | 6 | 8 | 9 | 8 | 8 | 6 | 4 | 2 | 1 |
| Lyon UVI | 2 | 3 | 5 | 6 | 8 | 10 | 9 | 8 | 6 | 5 | 3 | 2 |
| Nice UVI | 2 | 4 | 6 | 7 | 8 | 10 | 9 | 8 | 7 | 5 | 3 | 2 |
| Marseille UVI | 2 | 4 | 5 | 7 | 9 | 10 | 9 | 8 | 7 | 5 | 3 | 2 |
| Toulouse UVI | 2 | 4 | 6 | 7 | 9 | 10 | 10 | 9 | 7 | 5 | 3 | 2 |