UV Index in Los Altos, United States

Last updated: June 2, 2025

In Los Altos, United States, being aware of the UV Index is crucial for your skin health and sun safety. Understanding UV levels helps you take proactive measures to prevent sunburn and long-term skin damage. With its Csb climate, Los Altos experiences a unique balance of sun exposure, particularly during the mid-day hours when the UV Index peaks at a dangerous 11. Knowing when the UV levels rise can empower you to protect yourself and enjoy the beautiful California sun responsibly!

Hourly UV Index in Los Altos

The UV Index today paints a vivid picture of solar intensity, peaking dramatically between 12:00 PM and 2:00 PM with a striking 11—a warning to seek shade and protect skin. Starting the day at a gentle 1 at 7:00 AM, the index gradually climbs, reaching 4 by 9:00 AM and escalating to 9 by 11:00 AM. As the sun reaches its zenith, the index hits 11, indicating extreme conditions that persist for a solid three hours. Following this midday blast, it gracefully declines to 6 by 4:00 PM, before tapering off to a safer 1 by the evening. Remember to stay sun-smart 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.
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	11	extreme	10 min
13:00	11	extreme	10 min
14:00	11	extreme	10 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 Los Altos

The UV Index experiences significant seasonal variation, with the highest risks typically occurring from March to August. During this period, the UV Index peaks at 11, indicating an extreme exposure category in June and July, where the burn time is as short as 10 minutes. Conversely, the months of January, November, and December present a lower risk with a moderate UV Index of 3 to 5, allowing for burn times up to 30 minutes. It is crucial for both visitors and residents to monitor the UV Index regularly, especially during the high-risk months, and to take appropriate sun protection measures, such as wearing sunscreen, protective clothing, and seeking shade during peak hours to prevent skin damage.

Monthly Maximum UV Index for Los Altos, United States

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

The table above highlights how UV exposure in Los Altos 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.

Los Altos'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 Altos	3	5	8	9	10	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