As of 11:30 AM CST on November 25, 2025, all 15 cities in Mercer County, IL in our database have a UV Index reading of Low. The city with the highest UV Index reading right now is Viola, IL with a reading of 1.4.
Over the next 24 hours, the highest UV Index reading in Mercer County, IL is expected to be 1.4 in Viola between 11:00 AM - 12:00 PM CST today.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |