As of 2:28 PM EDT on March 11, 2026, all 18 cities in Mercer County, PA in our database have a UV Index reading of Low. The city with the highest UV Index reading right now is Greenville, PA with a reading of 1.3.
Over the next 24 hours, the highest UV Index reading in Mercer County, PA is expected to be 4.3 in Hermitage between 1:00 PM - 2:00 PM EDT tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |