As of 7:56 PM MDT on June 15, 2026, all 10 cities in Jefferson County, MT in our database have a UV Index reading of Low. The city with the highest UV Index reading right now is Basin, MT with a reading of 1.1.
Over the next 24 hours, the highest UV Index reading in Jefferson County, MT is expected to be 10.5 in Basin between 2:00 PM - 3:00 PM MDT tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |