As of 12:52 PM CDT on June 27, 2026, out of 32 cities in St. Clair County, IL in our database, 22 cities (69%) have a UV Index reading of Very High, while 10 cities (31%) have a UV Index reading of High. The city with the highest UV Index reading right now is New Athens, IL with a reading of 7.8.
Over the next 24 hours, the highest UV Index reading in St. Clair County, IL is expected to be 8.1 in Mascoutah between 11:00 AM - 12:00 PM CDT tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |