UV Index in O'Fallon, United States

Last updated: August 1, 2025

Understanding the UV Index in O'Fallon, Missouri, is essential for protecting your skin and maintaining overall health. With peaks reaching an intense 11 during midday, awareness of UV levels can help you prevent painful sunburns and long-term skin damage. O'Fallon's humid subtropical climate (Cfa) means residents are often exposed to high levels of ultraviolet radiation, particularly in the summer months. By monitoring the UV Index, you can take proactive steps to enjoy the outdoors safely, ensuring your skin stays healthy while you soak up the sun!

Hourly UV Index in O'Fallon

The UV Index throughout the day follows a predictable rise and fall, peaking at 11 around 1:00 PM. Starting at a modest 1 at 7:00 AM, it gradually escalates, reaching 10 by 12:00 PM, signaling the need for sun protection. As the afternoon progresses, the index dips from 11 to 8 by 3:00 PM, then declines further to 2 by 6:00 PM, and finally settles back at 1 by 7:00 PM. This data underscores the importance of taking precautions during the hours of peak UV exposure, particularly between 11:00 AM and 3:00 PM, when levels are highest and pose the greatest risk to skin health.

Average solar exposure data for the current time of the year. Actual values may vary and depend on many factors, such as cloud cover, vegetation cover, surface type, etc.
TimeUVICategoryTime to Burn
07:001low45 min
08:001low45 min
09:003moderate30 min
10:005moderate30 min
11:007high25 min
12:009very high15 min
13:009very high15 min
14:009very high15 min
15:007high25 min
16:005moderate30 min
17:003moderate30 min
18:002low45 min
19:001low45 min

Monthly UV Index Trends in O'Fallon

Throughout the year, the UV Index exhibits noticeable seasonal changes, with the highest risk months being April to August, when the index reaches extreme levels of 10 and 11. During these peak months, particularly in June and July, the burn time shortens significantly to just 10 minutes, necessitating extra caution. In contrast, the winter months (January, February, and December) see moderate UV levels with burn times of 30 minutes. It is advisable for both visitors and residents to take protective measures, such as wearing sunscreen and protective clothing, especially from March to September, when the potential for skin damage from UV exposure becomes particularly high.

Monthly Maximum UV Index for O'Fallon, United States

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in O'Fallon. It measures the strength of ultraviolet radiation from the sun and helps assess the risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec356910111198653
Data source: Statistical UV Index data for O'Fallon, based on information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

Compare O'Fallon UV Index with Other United States Cities

The table above highlights how UV exposure in O'Fallon compares to other major locations across United States. This comparison helps travelers and residents better understand regional sun intensity and plan outdoor activities with sun safety in mind.
O'Fallon's solar exposure compared to other cities in United States. Generated using Copernicus Atmosphere Monitoring Service information.
 JanFebMarAprMayJunJulAugSepOctNovDec
Chicago UVI34689101098642
Brooklyn UVI35681010998642
New York City UVI35681010998642
O'Fallon3569101111109653
Los Angeles UVI46891011111010754
Houston UVI589111112121110975