As of 3:54 PM MDT on June 4, 2026, out of 31 cities in Boulder County, CO in our database, 26 cities (84%) have a UV Index reading of Moderate, 4 cities (13%) have a UV Index reading of High, while 1 city (3%) have a UV Index reading of Very High. The city with the highest UV Index reading right now is Longmont, CO with a reading of 7.5.
Over the next 24 hours, the highest UV Index reading in Boulder County, CO is expected to be 10.9 in Nederland 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 |