As of 4:03 PM EDT on June 30, 2025, out of 17 cities in Mercer County, NJ in our database, 16 cities (94%) have a UV Index reading of Low, while 1 city (6%) have a UV Index reading of Moderate. The city with the highest UV Index reading right now is Hopewell, NJ with a reading of 4.5.
Over the next 24 hours, the highest UV Index reading in Mercer County, NJ is expected to be 10.2 in Twin Rivers 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 |