As of 11:33 PM CDT on June 22, 2025, all 32 cities in St. Clair County, IL in our database have a UV Index reading of 0, indicating no radiation from the sun.
Over the next 24 hours, the highest UV Index reading in St. Clair County, IL is expected to be 10.7 in Mascoutah between 1:00 PM - 2:00 PM CDT tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |