As of 12:38 PM CDT on March 21, 2026, all 5 cities in Williamson County, TN in our database have a UV Index reading of High. The city with the highest UV Index reading right now is Thompson's Station, TN with a reading of 5.7.
Over the next 24 hours, the highest UV Index reading in Williamson County, TN is expected to be 6 in Franklin between 1:00 PM - 2:00 PM CDT today.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |