UV Index
UV Index
Today's UV index in O'Fallon, United States 
will be up to 9.7, indicating a very high level of sun exposure for the average person. Check our tips for today to make sure you're safe in the sun.
Last checked: 2025-07-12
With a UV index of 9.7 in O'Fallon, it's crucial to safeguard your skin from harmful UV rays. Protect yourself by minimizing sun exposure, wearing protective clothing, and applying SPF 30+ sunscreen every 2 hours.
O'Fallon, United States, has a UV index that varies throughout the year, generally reaching moderate to high levels during summer months and lower levels in winter, reflecting typical seasonal sun exposure patterns.
The city experiences four distinct seasons: warm, humid summers with temperatures often in the 80s and 90s (Fahrenheit), cool to cold winters with occasional snow, and mild spring and fall with changing foliage and moderate rainfall.
Compared to the wider Midwest region and nearby states, O'Fallon has similar weather patterns but can be slightly warmer in summer and colder in winter than areas further south, while sharing humidity and precipitation trends common to this part of the U.S.
See the UV index hour by hour for O'Fallon, along with the temperature and how cloudy it is. If the UV level is higher than moderate, it's best to avoid direct sunlight.