As of 5:12 PM CDT on September 19, 2026, all 14 cities in Jefferson County, WI in our database have a UV Index reading of Low. The city with the highest UV Index reading right now is Watertown, WI with a reading of 0.2.
Over the next 24 hours, the highest UV Index reading in Jefferson County, WI is expected to be 5.2 in Ixonia between 1:00 PM - 2:00 PM CDT tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |