Last updated: July 2, 2025
In Chamonix-Mont-Blanc, France, staying informed about the UV Index is crucial for protecting your skin against harmful ultraviolet rays. Understanding UV levels helps prevent sunburn and maintain skin health, especially in the high-altitude environment of the Alps, where UV exposure is intensified. With a Dfc climate characterized by cold summers and significant UV risks, particularly during midday hours when the index peaks at a staggering 10, awareness of these fluctuations is essential. By keeping an eye on the UV Index, you can enjoy the breathtaking mountain landscapes while safeguarding your skin from the sun's harmful effects.
As the sun rises, the UV Index begins its steady ascent, starting at a mild 1 at 7:00 AM. By 8:00 AM, it reaches 2, hinting at the day ahead. As we approach mid-morning, the intensity climbs to 3 by 9:00 AM and then dramatically spikes to 5 at 10:00 AM. The real peak occurs between 12:00 PM and 2:00 PM, where the index soars to a whopping 10, indicating strong sun exposure. This midday intensity begins to taper off by 3:00 PM, as it drops to 9, and continues to slide through the late afternoon, ending the day at 1 by 7:00 PM. It's crucial to stay protected during those peak hours to enjoy the sun safely!
| 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 | 1 | low | 45 min |
As the seasons change, so does the UV Index, reflecting varying levels of sun exposure risk. From January to February, the UV Index remains relatively moderate, with a value of 3-4 and a burn time of 30 minutes. However, starting in March, the UV Index rises significantly, reaching high levels of 7 and subsequently peaking at 10 in June and July, marking the months of highest risk. April to August features very high UV Index ratings (8-10), with a critical burn time of only 15 minutes, making it essential for visitors and residents to take precautionary measures by wearing sunscreen, hats, and protective clothing during these months. With a decline in UV exposure in September (7) and further into the fall and winter months, the UV Index drops to moderate (5) in October and then to low (2) by December, allowing for safer outdoor activities. Overall, it is crucial to be vigilant, especially during the high-risk months of March through August, to ensure skin protection against harmful UV radiation.
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 |
| Toulouse UVI | 2 | 4 | 6 | 7 | 9 | 10 | 10 | 9 | 7 | 5 | 3 | 2 |
| Chamonix-Mont-Blanc | 3 | 4 | 7 | 8 | 9 | 10 | 10 | 9 | 7 | 5 | 3 | 2 |