UV Index in Alton, United States

Last updated: July 2, 2025

Understanding the UV Index is crucial for residents of Alton, United States, particularly as the warm climate of the Cfa zone presents unique sun exposure challenges. With peak UV levels reaching 11 at midday, awareness of UV risks is essential for preventing sunburn and promoting overall skin health. Knowing when to seek shade, wear protective clothing, or apply sunscreen can make all the difference during those sunny days, ensuring that you enjoy Alton's beautiful weather while safeguarding your skin against the harmful effects of UV radiation.

Hourly UV Index in Alton

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.
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	8	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 Alton

Throughout the year, the UV Index experiences notable seasonal fluctuations, which are particularly prominent in the spring and summer months. High-risk months for UV exposure include April through August, with the index peaking in June and July at 11, categorized as extreme exposure, where the burn time is a mere 10 minutes. As the summer wanes into fall, the UV Index gradually declines, with October reflecting a high category and increased burn times of 25 minutes. Residents and visitors should take precautions during the high-risk months, such as applying broad-spectrum sunscreen, wearing protective clothing, and seeking shade during peak hours to minimize the risk of skin damage.

Monthly Maximum UV Index for Alton, United States

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

The table above highlights how UV exposure in Alton 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.

Alton'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
Alton	3	5	6	9	10	11	11	9	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