Last updated: July 2, 2025
Understanding the UV Index is essential for residents and visitors in Rennes, France, as it plays a pivotal role in promoting skin health and preventing sunburn. As the UV levels rise, particularly during midday hours, awareness becomes crucial for enjoying the outdoors safely. Rennes experiences a temperate maritime climate, which can lead to varying UV exposure risks throughout the year. With peak UV Index values soaring to 9 during summer afternoons, vigilant sun protection measures can safeguard your skin and enhance your outdoor experiences in this vibrant city.
As the sun rises, the UV Index begins at a gentle 1 at 07:00, remaining low until 09:00 when it climbs to 2. By 10:00, with the sun reaching its peak, the index escalates to 3, but the real intensity hits by 12:00, soaring to 7. The peak occurs at 14:00, where the UV Index peaks at an impressive 9, signaling a high need for sun protection. Even as the afternoon wanes, levels stay elevated, measuring 8 at 15:00 and gradually decreasing to 5 by 17:00. As the day draws to a close, the UV Index drops to 2 by 19:00, making way for a cooler evening. It's crucial to stay vigilant throughout the day, especially during those mid-afternoon hours!
| 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 | 3 | moderate | 30 min |
| 11:00 | 5 | moderate | 30 min |
| 12:00 | 7 | high | 25 min |
| 13:00 | 8 | very high | 15 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 4 | moderate | 30 min |
| 19:00 | 2 | low | 45 min |
Throughout the year, UV exposure fluctuates significantly, with the highest risk months occurring from May to August, when the UV Index reaches levels categorized as very high (UV Index 8-9). During these months, the burn time drastically decreases to just 15 minutes, emphasizing the need for protection. Conversely, the low risk months of January, November, and December offer a safer environment with a UV Index of 2 and a burn time of 45 minutes. As such, visitors and residents should be particularly vigilant during peak summer months by wearing sunscreen, protective clothing, and seeking shade during peak sun hours, while enjoying the milder winter months with less concern for UV exposure.
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 |
| Rennes | 2 | 3 | 5 | 6 | 8 | 9 | 9 | 8 | 6 | 4 | 2 | 2 |
| 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 |