UV Index in Alton, United States

Last updated: August 1, 2025

In Alton, United States, being aware of the UV Index is crucial for protecting your skin and maintaining overall health. Understanding UV levels helps you avoid sunburn and long-term skin damage, ensuring you enjoy the sun safely. With a humid subtropical climate (Cfa) that often brings high UV exposure, particularly during midday hours when levels can soar to 11, it's essential to monitor the UV Index regularly. By keeping track of these values, residents can make informed decisions about sun safety—whether that means seeking shade, wearing protective clothing, or applying sunscreen. Stay vigilant and protect your skin in the sunny days ahead!

Hourly UV Index in Alton

The UV Index for today shows a dramatic rise as the sun ascends into the sky. Starting at a mild 1 by 07:00, the index gradually builds, reaching 3 by 09:00 and peaking at an intense 11 at 13:00—a level where sun protection is crucial. From this pinnacle, the values start to decline, tapering off to 10 at 14:00 and then gradually decreasing through the afternoon and evening, with values of 6 at 16:00 and sliding down to 1 by 19:00. Plan your outdoor activities accordingly, and remember to protect your skin during those peak hours!

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.
TimeUVICategoryTime to Burn
07:001low45 min
08:001low45 min
09:003moderate30 min
10:005moderate30 min
11:007high25 min
12:009very high15 min
13:0010very high15 min
14:0010very high15 min
15:008very high15 min
16:005moderate30 min
17:003moderate30 min
18:002low45 min
19:001low45 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.
JanFebMarAprMayJunJulAugSepOctNovDec46710111111109753
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.
 JanFebMarAprMayJunJulAugSepOctNovDec
Chicago UVI34689101098642
Brooklyn UVI35681010998642
New York City UVI35681010998642
Alton36710111111109753
Los Angeles UVI46891011111010754
Houston UVI589111112121110975