Last updated: August 1, 2025
Understanding the UV Index is essential for residents of Saint Charles, United States, as it plays a critical role in maintaining skin health and preventing sunburns. With a climate classified as Cfa, Saint Charles experiences varying UV levels throughout the day, peaking sharply around midday. As UV exposure can lead to significant skin damage over time, knowing when to seek shade or apply sunscreen is crucial for protecting your skin and overall health. Be mindful of the rising UV levels—especially when they hit a maximum of 10 between noon and 2 PM—to ensure you enjoy the sun safely!
The UV Index data unveils a dynamic progression of sun intensity throughout the day. Starting low at 1 at 07:00, the index gradually escalates, reaching maximum levels of 10 between 12:00 and 14:00. This peak signals a critical time for sun protection. As the afternoon wanes, the index tapers off to 8 at 15:00, and then descends further to 3 by 17:00, and 2 by 18:00. Ultimately, the day concludes softly with a return to 1 at 19:00. It's essential to stay vigilant during those peak hours to safeguard your skin while enjoying the sun!
| 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 | 9 | very high | 15 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, seasonal UV changes indicate varying levels of sun exposure risk. The high-risk months are from April to September, with UV Index values reaching very high to extreme levels, particularly in June when the UV Index peaks at 11. Visitors and residents should take necessary precautions during these months, such as seeking shade, wearing protective clothing, and using sunscreen with a high SPF. In contrast, January, February, November, and December present a moderate exposure risk, allowing for more extended sun exposure times of up to 30 minutes without significant risk of burning. It's essential to remain vigilant year-round and adjust sun protection strategies based on the UV Index to maintain skin health.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 |
| Saint Charles | 3 | 5 | 6 | 9 | 10 | 11 | 10 | 10 | 9 | 6 | 4 | 3 |
| 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 |