As of 10:27 AM CDT on September 18, 2026, out of 8 cities in Boone County, IL in our database, 5 cities (63%) have a UV Index reading of Moderate, while 3 cities (38%) have a UV Index reading of Low. The city with the highest UV Index reading right now is Belvidere, IL with a reading of 2.9.
Over the next 24 hours, the highest UV Index reading in Boone County, IL is expected to be 6.2 in Belvidere between 1:00 PM - 2:00 PM CDT today.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |