UV Index in O'Fallon, United States

Last updated: June 2, 2025

Having a clear understanding of the UV Index is essential for residents of O'Fallon, United States, as it directly impacts sun safety and skin health. High UV levels, especially between 11 AM and 3 PM, can result in painful sunburns and long-term skin damage if precautions aren’t taken. With O'Fallon's humid subtropical climate, the risks increase during summer months when UV exposure is at its peak. By staying informed about the UV Index, you can enjoy the sunny outdoors while effectively protecting yourself and your loved ones from harmful UV rays.

Hourly UV Index in O'Fallon

The UV Index data highlights a dramatic rise in sun intensity as the day progresses. Starting early at 1 around 7:00 AM, it gradually climbs to 10 by noon, peaking at a staggering 11 at 1:00 PM. This is the moment when UV exposure becomes most concerning, emphasizing the importance of sun protection. As the afternoon unfolds, the index gracefully tapers down, dipping to 8 by 3:00 PM and further declining to 4 by 5:00 PM. By the time evening rolls in, the UV Index settles back to 1 at 7:00 PM, signaling a reprieve from the midday sun. This data can be a crucial guide for planning outdoor activities safely throughout the day.

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.
Time	UVI	Category	Time to Burn
07:00	1	low	45 min
08:00	2	low	45 min
09:00	4	moderate	30 min
10:00	6	high	25 min
11:00	9	very high	15 min
12:00	10	very high	15 min
13:00	11	extreme	10 min
14:00	10	very high	15 min
15:00	8	very high	15 min
16:00	6	high	25 min
17:00	4	moderate	30 min
18:00	2	low	45 min
19:00	1	low	45 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.

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.
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Chicago UVI	3	4	6	8	9	10	10	9	8	6	4	2
Brooklyn UVI	3	5	6	8	10	10	9	9	8	6	4	2
New York City UVI	3	5	6	8	10	10	9	9	8	6	4	2
O'Fallon	3	5	6	9	10	11	11	10	9	6	5	3
Los Angeles UVI	4	6	8	9	10	11	11	10	10	7	5	4
Houston UVI	5	8	9	11	11	12	12	11	10	9	7	5