UV Index in Alton, United States

Last updated: July 2, 2025

Understanding the UV Index is crucial for residents of Alton, United States, where sunny days are common in the BSh climate zone. Knowledge of UV levels can significantly aid in sunburn prevention and promote long-term skin health, empowering you to make informed decisions about sun exposure. With an intense peak UV Index of 12 around noon, knowing when to seek shade or apply sunscreen is essential for protecting your skin from damaging rays. Stay aware and safeguard your skin while enjoying the sunny days that Alton has to offer!

Hourly UV Index in Alton

As the sun rises, the UV Index slowly climbs, starting at a low 1 at 07:00 and 08:00. By 09:00, it slightly increases to 2. However, the real intensity kicks in as the day progresses, peaking at an impressive 12 between 13:00 and 14:00. This is the critical time when sun protection is essential, given the dangerous exposure level. As the afternoon wanes, the index starts to decrease, dropping to 10 by 15:00 and further declining to 5 at 17:00. Finally, as the sun sets, it returns to a mild 1 by 19:00. Take note of these fluctuations, as they are crucial for staying safe under the sun!

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	1	low	45 min
09:00	2	low	45 min
10:00	5	moderate	30 min
11:00	8	very high	15 min
12:00	10	very high	15 min
13:00	12	extreme	10 min
14:00	12	extreme	10 min
15:00	10	very high	15 min
16:00	8	very high	15 min
17:00	5	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 fluctuates significantly, with high-risk months typically falling between February and September. During this time, values soar to extreme levels of 12, especially in May through August, where the recommended burn time is only 10 minutes. In March and April, the index remains in the very high to extreme categories, with burn times decreasing to just 10-15 minutes. As summer gradually transitions into fall, the UV Index begins to decline, allowing for slightly longer burn times in October at 15 minutes, but still indicating a very high risk. For winter months, January, November, and December maintain a high exposure category but extend burn times back to 25 minutes. Visitors and residents should remain vigilant, particularly during the peak UV months, taking proactive measures such as wearing sunscreen, protective clothing, and seeking shade during peak hours to mitigate the risks associated with intense sun exposure.

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
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
Alton	6	9	10	11	12	12	12	12	11	9	7	6