As of 2:41 PM CDT on April 24, 2026, all 15 cities in Mercer County, IL in our database have a UV Index reading of High. The city with the highest UV Index reading right now is Keithsburg, IL with a reading of 6.9.
Over the next 24 hours, the highest UV Index reading in Mercer County, IL is expected to be 6.9 in Keithsburg between 2:00 PM - 3:00 PM CDT today.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |