As of 9:22 PM MST on December 16, 2025, all 2 cities in Custer County, MT in our database have a UV Index reading of 0, indicating no radiation from the sun.
Over the next 24 hours, the highest UV Index reading in Custer County, MT is expected to be 0.8 in Ismay between 11:00 AM - 12:00 PM MST tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |