UV Index in St. Louis, United States

Last updated: June 2, 2025

Understanding the UV Index in St. Louis is crucial for safeguarding your skin against harmful ultraviolet radiation. With peak levels soaring to 11 during the midday hours, awareness of UV intensity is vital for preventing sunburn and promoting long-term skin health. Given St. Louis's humid subtropical climate, residents and visitors alike should be mindful of the elevated UV risks, especially in the summer months. Stay informed and enjoy the sun safely by checking the UV Index before stepping outdoors!

Hourly UV Index in St. Louis

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 St. Louis

Throughout the year, seasonal UV changes indicate varying levels of sun exposure risk. The high-risk months are from April to September, with UV Index values reaching very high to extreme levels, particularly in June when the UV Index peaks at 11. Visitors and residents should take necessary precautions during these months, such as seeking shade, wearing protective clothing, and using sunscreen with a high SPF. In contrast, January, February, November, and December present a moderate exposure risk, allowing for more extended sun exposure times of up to 30 minutes without significant risk of burning. It's essential to remain vigilant year-round and adjust sun protection strategies based on the UV Index to maintain skin health.

Monthly Maximum UV Index for St. Louis, United States

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in St. Louis. 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 St. Louis, 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 St. Louis UV Index with Other United States Cities

The table above highlights how UV exposure in St. Louis 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.

St. Louis'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
St. Louis	3	5	6	9	10	11	10	10	9	6	4	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