UV Index in Waltham, United States

Last updated: May 3, 2025

Understanding the UV Index is crucial for residents of Waltham, United States, as it plays a significant role in overall skin health and sunburn prevention. With the climate falling under the Dfa zone, Waltham experiences a mix of seasonal variations that can impact UV levels throughout the year. As daily UV Index readings can peak at 9 around noon, it's essential to be aware of these fluctuations to protect your skin from harmful effects. Being informed about UV exposure not only helps you enjoy the outdoors safely but also promotes a healthier lifestyle in the sunny spots of Waltham.

Hourly UV Index in Waltham

The UV Index for today presents an intriguing journey through the hours. It starts off gently at 1 at 07:00, but as the morning progresses, it climbs swiftly to 2 by 08:00 and reaches a moderate 4 at 09:00. The sun intensifies its rays further, peaking at a robust 9 between 12:00 and 13:00—a reminder to take precautions against harmful UV exposure. Following this peak, the index gradually descends, dipping to 6 at 15:00, and mellowing down to 1 by 18:00. This pattern highlights the importance of seeking shade or applying sunscreen during the midday hours when UV radiation is most potent.

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	8	very high	15 min
12:00	9	very high	15 min
13:00	9	very high	15 min
14:00	8	very high	15 min
15:00	6	high	25 min
16:00	4	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 Waltham

Throughout the year, the UV Index demonstrates significant seasonal changes, particularly peaking in the summer months. Notably, April to August presents the highest risk for UV exposure, with May and June reaching a maximum of 10, categorized as very high risk, where the burn time drops to just 15 minutes. Visitors and residents should be especially cautious during these months, ensuring they wear protective clothing, apply broad-spectrum sunscreen, and seek shade during peak hours. Conversely, the UV Index declines from September onwards, dropping to a low of 2 in December, which indicates reduced risk. It is advisable to remain vigilant year-round, adapting sun safety practices according to the current UV levels to ensure optimal skin protection.

Monthly Maximum UV Index for Waltham, United States

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

The table above highlights how UV exposure in Waltham 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.

Waltham'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
Waltham	3	5	5	8	9	10	9	9	7	6	4	2
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