As of 6:26 PM EDT on May 18, 2026, all 8 cities in Gratiot County, MI in our database have a UV Index reading of Low. The city with the highest UV Index reading right now is St. Louis, MI with a reading of 0.2.
Over the next 24 hours, the highest UV Index reading in Gratiot County, MI is expected to be 7.4 in Perrinton between 2:00 PM - 3:00 PM EDT tomorrow.
| Range | 0 - 2 | 3 - 5 | 6 - 7 | 8 - 10 | 11+ |
|---|---|---|---|---|---|
| Color | |||||
| Risk | Low | Moderate | High | Very High | Extreme |