As of 10:16 AM CDT on June 9, 2026, out of 18 cities in Williamson County, TX in our database, 17 cities (94%) have a UV Index reading of Moderate, while 1 city (6%) have a UV Index reading of Low. The city with the highest UV Index reading right now is Thrall, TX with a reading of 4.
Over the next 24 hours, the highest UV Index reading in Williamson County, TX is expected to be 12 in Round Rock 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 |