Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors in Grenoble, France, where the stunning alpine scenery can often lead to increased sun exposure. Awareness of UV levels is essential—not only for preventing painful sunburns but also for protecting your skin health over the long term. In Grenoble's Cfb climate, sunny summer days can see UV indices soar to a maximum of 10 around midday, posing significant risks for overexposure. By staying informed about the daily UV ratings, you can enjoy the beautiful outdoors while safeguarding your skin from harmful effects.
As the sun rises, the UV Index begins its ascent, starting at a modest 1 at 07:00 and gradually climbing throughout the morning. By 10:00, it reaches 5, signaling the time to lather on that sunscreen. The peak arrives between 13:00 and 14:00, hitting a maximum of 10, indicating that protective measures are essential. As the afternoon progresses, the index dips slightly to 9 at 15:00, and continues to decline, reaching 3 by 18:00. By the time the sun sinks, the UV threat diminishes to 2 at 19:00, making it clear that midday sun worshippers should be particularly cautious, while evening strollers can enjoy the waning rays with less concern.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | 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 | 5 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 2 | low | 45 min |
Throughout the year, seasonal changes in UV exposure highlight significant fluctuations in the UV Index. The months of May through August are particularly high-risk, with UV Index values reaching a peak of 10, indicating very high exposure and a burn time of only 15 minutes. Visitors and residents should remain vigilant during these months, employing protective measures such as sunscreen and clothing, especially between 10 AM and 4 PM when UV exposure is strongest. March and April also show increased risk with UV Index values of 6 and 7 respectively. Conversely, January and December present lower risk levels, with UV Index values of 2 indicating low exposure and longer potential burn times of 45 minutes. It is essential to monitor UV levels year-round and adjust sun protection strategies accordingly to ensure safety.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 |
| Grenoble | 2 | 4 | 6 | 7 | 9 | 10 | 10 | 9 | 7 | 5 | 3 | 2 |
| Toulouse UVI | 2 | 4 | 6 | 7 | 9 | 10 | 10 | 9 | 7 | 5 | 3 | 2 |