As of 5:42 PM MDT on June 18, 2026, all 18 cities in Gallatin County, MT in our database have a UV Index reading of Moderate. The city with the highest UV Index reading right now is Big Sky, MT with a reading of 4.5.
Over the next 24 hours, the highest UV Index reading in Gallatin County, MT is expected to be 10.5 in Hebgen Lake Estates 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 |