UV Index in Alton, United States

Last updated: June 2, 2025

In Alton, United States, being aware of the UV Index is crucial for maintaining skin health and preventing sunburn, especially during the peak summer months. Understanding UV levels helps residents and visitors alike take the proper precautions against harmful sun exposure. With a humid subtropical climate, Alton typically experiences high UV rays, peaking at a significant 11 from noon to early afternoon. This makes it essential for everyone to stay informed about daily UV fluctuations and to adopt protective measures, ensuring a safe and enjoyable outdoor experience under the sun.

Hourly UV Index in Alton

As the sun rises, the UV Index gradually climbs, starting at a mild 1 at 07:00. By 09:00, it reaches a moderate 4, signaling a need for some sun protection. The intensity peaks at 12:00 with a powerful 10, indicating strong sunlight. The highest point, 11 at 13:00, urges sun safety awareness as the afternoon sun bears down. However, relief comes as the sun begins to set; the index dips to 9 by 15:00, then gradually decreases to 4 at 17:00, and finally back to a safe 1 by 19:00. Throughout the day, staying vigilant against UV exposure is key!

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	9	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 varies significantly, with high-risk months occurring primarily from April to August, where the index reaches extreme levels of 10-11. During these months, the recommended burn time drastically decreases, dropping to as low as 10 minutes of unprotected sun exposure. Visitors and residents are advised to take extra precautions during these high UV Index periods by wearing protective clothing, applying sunscreen with a high SPF, and seeking shade during peak hours (10 AM to 4 PM). As the UV Index returns to moderate levels in January, November, and December, the risk of skin damage decreases, but sun safety remains essential year-round.

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	6	7	10	11	11	11	10	9	7	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