UV Index in Walnut, United States

Last updated: August 1, 2025

Understanding the UV Index in Walnut, United States, is crucial for protecting your skin and overall health. With UV levels peaking at a hazardous 11 during midday, it's vital to stay informed about sun exposure to prevent sunburn and long-term skin damage. Walnut's Cfa climate, characterized by warm summers and mild winters, can lead to increased UV exposure, especially during peak hours. By staying aware of the UV Index, you can take proactive steps to enjoy the outdoors safely while protecting your skin from harmful effects.

Hourly UV Index in Walnut

The UV Index steadily climbs as the day progresses, starting from a mild 1 at 7:00 AM and reaching a peak of 11 by 1:00 PM. Sun-seekers and outdoor enthusiasts should be mindful, as the index hits a high of 10 at 12:00 PM, signaling significant UV exposure. After this peak, the index gradually decreases, dropping to 8 by 3:00 PM, and continuing to decline to 1 by 7:00 PM. For safe sun enjoyment, it’s best to take precautions during those high UV hours, particularly between 11:00 AM and 2:00 PM. Remember to sport your hats and sunscreen!

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	3	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	10	very high	15 min
14:00	10	very high	15 min
15:00	8	very high	15 min
16:00	5	moderate	30 min
17:00	3	moderate	30 min
18:00	1	low	45 min
19:00	1	low	45 min

Monthly UV Index Trends in Walnut

Throughout the year, the UV Index exhibits significant seasonal changes, with the highest levels occurring in May, June, and July, where it reaches an extreme index of 11. These months pose the greatest risk for sunburn, with a quick burn time of just 10 minutes. The high-risk months to be particularly cautious are March through August, as the UV Index remains very high to extreme during this period. Visitors and residents should take proactive measures, including wearing protective clothing, applying broad-spectrum sunscreen, and seeking shade during peak sunlight hours, especially from 10 a.m. to 4 p.m. Conversely, in the winter months of December and January, the UV Index is lower at 3-4, indicating a moderate risk with a burn time of 30 minutes, allowing for slightly more leeway in sun exposure. Regardless of the season, it is essential to stay informed and protect yourself from harmful UV rays.

Monthly Maximum UV Index for Walnut, United States

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

The table above highlights how UV exposure in Walnut 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.

Walnut'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
Walnut	4	6	8	10	11	11	11	10	9	7	5	3
Houston UVI	5	8	9	11	11	12	12	11	10	9	7	5