UV Index in Princeton, United States

Last updated: June 2, 2025

Understanding the UV Index in Princeton, United States is crucial for safeguarding your skin while enjoying the outdoors. With UV levels peaking as high as 11 during midday, it's essential to be aware of the potential risks for sunburn and long-term skin damage. The humid subtropical climate typical of Princeton means that UV exposure can be intense, especially during the summer months. By keeping an eye on the daily UV Index, you can take proactive steps to protect your skin and maintain your overall health while soaking up the sun.

Hourly UV Index in Princeton

As the sun rises, the UV Index starts off gently at 1 by 7:00 AM, gradually climbing as the day progresses. By 10:00 AM, it reaches 6, signaling a notable increase in solar radiation. The intensity peaks at 12:00 PM with a striking 10 and continues to soar to a maximum of 11 at 1:00 PM, marking the hour of greatest exposure. As the afternoon unfolds, the index begins to taper off—dropping to 10 at 2:00 PM and 8 by 3:00 PM. By late afternoon, the UV Index gracefully descends to 4 at 5:00 PM, settling back to 2 by 6:00 PM and finally returning to a gentle 1 by 7:00 PM. This highlights the importance of sun protection during mid-day when UV rays are at their most intense.

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	11	extreme	10 min
14:00	10	very high	15 min
15:00	8	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 Princeton

Throughout the year, the UV Index exhibits significant variations, with high-risk months occurring from March to August, where the index reaches very high to extreme levels. In March and April, the UV Index peaks at 10, and it escalates to 11 in June and July, indicating an urgent need for sun protection since the burn time drops to just 10 minutes during these months. The risk decreases in the fall and winter, with November and December showing moderate levels (UV Index of 5 and 3, respectively) and extended burn times of 30 minutes. To ensure safety, visitors and residents are advised to take extra precautions during the high-risk months by wearing sunscreen, protective clothing, and seeking shade, while enjoying outdoor activities to minimize the risk of 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
Los Angeles UVI	4	6	8	9	10	11	11	10	10	7	5	4
Princeton	4	6	8	10	10	11	11	10	9	8	5	3
Houston UVI	5	8	9	11	11	12	12	11	10	9	7	5