As of 8:36 PM EDT on September 28, 2026, all 18 cities in Mercer County, PA 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 Mercer County, PA is expected to be 4.4 in Greenville between 2:00 PM - 3:00 PM EDT tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |