Last updated: July 2, 2025
Understanding the UV Index is crucial for residents of Saint Charles, United States, where the potential for harmful UV exposure can vary significantly throughout the day. Awareness of UV levels not only plays a vital role in sunburn prevention but also supports long-term skin health by encouraging safe sun practices. In this Dfb climate, characterized by distinct seasons, residents should be especially vigilant during peak sun hours when UV Index readings can soar to 10, indicating a high risk of harm from unprotected skin exposure. Stay informed and protected to enjoy the beauty of Saint Charles while safeguarding your skin!
The UV Index shows a clear trajectory of increasing intensity as the day unfolds. Starting from a mild level of 1 at 7:00 AM, it gradually ascends to 2 by 9:00 AM. The real surge occurs between 10:00 AM and 2:00 PM, peaking at a dangerous 10 at 2:00 PM, indicating a critical need for protection against harmful rays. As the sun begins to descend, the UV Index tapers off, declining to 5 by 5:00 PM, and finally settling back at 1 by 7:00 PM. This data serves as a reminder to stay vigilant under the sun, particularly during those peak hours when UV exposure can be at its highest.
| 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 | 8 | very high | 15 min |
| 13:00 | 9 | 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 do UV levels, highlighting periods of higher risk for sun exposure. From January to March, the UV Index remains low to moderate, with February seeing an increase. April to August marks the peak high-risk months, featuring very high UV levels, particularly in June and July, where the burn time drops to a remarkable 15 minutes. September transitions into a high UV category, while October to December see a gradual decline, returning to low risk by year's end. To protect yourself, especially during the high UV months of April through August, it is crucial to wear sunscreen, protective clothing, and seek shade to minimize exposure. Be particularly vigilant during the summer months when burn time is significantly reduced.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Saint Charles | 2 | 4 | 5 | 8 | 9 | 10 | 10 | 9 | 7 | 5 | 3 | 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 |