As of 1:10 PM CDT on May 29, 2026, all 12 cities in Johnson County, IA in our database have a UV Index reading of Very High. The city with the highest UV Index reading right now is Lone Tree, IA with a reading of 8.7.
Over the next 24 hours, the highest UV Index reading in Johnson County, IA is expected to be 8.9 in Frytown between 2:00 PM - 3:00 PM CDT today.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |