As of 5:46 PM MDT on May 26, 2026, out of 10 cities in Jefferson County, MT in our database, 6 cities (60%) have a UV Index reading of Low, while 4 cities (40%) have a UV Index reading of Moderate. The city with the highest UV Index reading right now is Montana City, MT with a reading of 2.6.
Over the next 24 hours, the highest UV Index reading in Jefferson County, MT is expected to be 8.1 in Boulder between 1:00 PM - 2:00 PM MDT tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |