UV Index in Princeton, United States

Last updated: June 2, 2025

Understanding the UV Index in Princeton, United States, is crucial for protecting your skin and ensuring overall health. With peak UV levels reaching as high as 11 during the midday hours, awareness is key to preventing sunburn and long-term skin damage. As a city in a Cfa climate zone, Princeton experiences humid summers that elevate UV exposure risks, making it essential to check daily UV readings. By staying informed about UV levels, you can enjoy the outdoors safely while minimizing health risks associated with excessive sun exposure.

Hourly UV Index in Princeton

The UV Index throughout the day reveals a dramatic rise in solar intensity. Starting at a mild 1 at 07:00, it climbs steadily, reaching 2 by 08:00. The real spike occurs as the sun climbs higher, with the index jumping to 4 at 09:00, before peaking at a striking 11 by 13:00—the highest risk of the day. After this peak, the UV levels gradually taper off, dropping to 8 at 15:00, and settling to a gentle 2 by 18:00. Remember to don that sunscreen during the midday hours to protect your skin from the sun’s powerful rays!

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	7	high	25 min
11:00	9	very high	15 min
12:00	10	very high	15 min
13:00	11	extreme	10 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	2	low	45 min
19:00	1	low	45 min

Monthly UV Index Trends in Princeton

The UV Index experiences significant seasonal variation, peaking in the spring and summer months. From April to September, the UV Index reaches very high levels, particularly in May and June, when it hits an extreme rating of 11. The high-risk months for UV exposure are April through September, with the lowest burn time of just 10 minutes occurring in May and June. As such, it's crucial for visitors and residents to take precautions during these months by wearing protective clothing, applying sunscreen regularly, and seeking shade, especially between 10 AM and 4 PM. In the fall and winter, the UV Index decreases to moderate levels, with safer exposure times returning. However, awareness is still essential year-round to prevent skin damage.

Monthly Maximum UV Index for Princeton, United States

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

The table above highlights how UV exposure in Princeton 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.

Princeton'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
Princeton	3	6	7	10	11	11	10	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